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Universal—courtesy Everett Collection

We’re a nation divided, with each side judging the other harshly, unable to empathize with the counterpart's point of view. And with each sure that their side's own values, methods and motives are more just, more reasonable, and just plain better. Sound familiar?

I’m not talking about politics in America. I’m talking about holiday shopping—specifically, when it should start. Several stores launched major holiday sales on the day after Halloween this year, and Santa, Rudolph, and Frosty started showing up in store aisles long beforehand, like mid-September. Live and let live? That's lost when it comes to what's acceptable for holiday shopping. There isn’t much in my field of consumer psychology that seems to stir up more angst than when and how people should shop for the holidays.

Joanne, an affluent 50-something empty-nester who I followed on a shopping trip to Costco for a recent research project, is a good example of someone who can't stand extra-early holiday season shopping. It was early October, and Joanne looked over at a fellow shopper examining a display of artificial Christmas trees and sighed. “Really? Why would she need a tree in October?" she said. "Some people are just insane when it comes to Christmas. This is just too early. It’s crazy.”

Joanne's reaction is fairly typical, as are the reasons for why the behavior of retailers and other consumers gets her upset. Underneath Joanne's contempt of October holiday shoppers is a fear that something she holds dear is being disrespected. For Joanne, the true meaning of the holidays revolve around family and the religious significance and traditions of Christmas. For others I’ve interviewed, angst springs from a fear that American life is over-commercialized, and that consumers are simply pawns at the mercy of greedy, manipulative retailers. Still others worry that two months of exposure to holiday merchandise in stores diminishes the impact of the season, and that Christmas will start to feel meaningless by mid-December.

Consumers like Joanne often think that early shoppers are neurotic or materialistic. They also frequently judge stores that stock holiday merchandise early as hollow, sacrilegious, opportunistic product pushers.

And yet, according to the National Retail Federation, more than 40% of Americans begin their holiday shopping before Halloween. No one's forcing them to do so. Could such a large percentage of our population truly be neurotic, materialistic, and/or easily manipulated, like Joanne suggests?

Read next: 5 Big Retail Trends That’ll Help 2015 Holiday Shoppers Grab the Best Deals

There are perfectly valid reasons why people embrace early-season holiday shopping. As part of this project I also interviewed Kerri, a working mother of two who travels frequently for work. When I asked her about holiday shopping, she said that starting early is the only way to get it all done. “I’ve always shopped for Christmas all year-round," she said. "Once it was because I could pick up special things when I traveled. Now that I have kids it’s just a necessity, and I’m glad I’m a good planner. I know people feel like the stores are pushing them, but I actually appreciate being able to pick up things for the holidays early so that I don’t have to make special trips later. I hate crowds!”

Kerri, like most early shoppers, is the opposite of what Joanne assumes about people who shop early. Kerri says that she loves Christmas and shops early because she guards her budget carefully and is afraid that if she procrastinates she’ll overspend out of panic. She also hates crowds and feels pressured when shopping during the holiday season. Contrary to what Joanne thinks, it’s Kerri’s respect for the holidays that propels her to shop early. “I don’t want to be one of those forlorn procrastinators that stops into a 24-hour drugstore on their way to a party hoping that a jug of bubble bath isn’t an inappropriate hostess gift,” Kerri told me.

Kerri, like Joanne, believes that shoppers who don’t do it her way have their priorities all wrong. Like many others who prefer to shop early, Kerri thinks that people who wait until December to plan Christmas meals and purchase decorations and gifts are procrastinators and poor planners. They also miss out on the enjoyment and spirit of the holidays because they’re out “battling crowds” at the mall. Kerri even thinks that the haters who say they are disgusted by early season shoppers are, in fact, secretly envious. “I’ll never be the one rushing to the post office, forced to pay higher prices for shipping because I didn’t plan ahead," she said. "I can understand why people feel jealous."

Then there are those who simply blame retailers for the constantly expanding holiday season. They bristle that promotions for every national holiday seem to start earlier every year. It’s not just Christmas Creep but now also Mother’s Day Creep and 4th of July Creep too. In fact, holiday creep is largely motivated by consumer behavior, and retailers are responding to their demands, which include their shopping needs being catered to anything, anywhere, on any device. It's a mentality I call IWWIWWIWI (I want what I want when I want it).

So, when should you start your holiday shopping? When it feels right for you—not so early that it spoils the festive holiday mood, and not so late that you'll be in a panic and make bad decisions. And here are a few tips to keep in mind to maximize the fun and minimize your expenditures.

BARGAINS. Retailers have not over-ordered this year. That means that sales will be promotional rather than designed to clear out unwanted merchandise. The result is that discounts won’t be as deep until right before Christmas, and the most coveted merchandise will probably sell out. So my advice is that if someone on your list wants a specific toy or pair of boots, don’t wait for a deep discount. Buy it as soon as possible. As for other goods, here’s what to expect:

• Right now retailers are still clearing out fall merchandise to make room to deck the halls. That means back-to-school items like jeans, sneakers, and office supplies are clearance priced.

• Black Friday and Cyber Monday are the best days of the year to buy cheap electronics. They’re often loss leaders (retailers are willing to sell them at a loss to get shoppers into their stores or on their websites), and the deals are often outstanding.

• Toys are typically not deeply discounted until a couple of weeks after Black Friday. There will be promotional 20% to 25% discounts throughout the shopping season.

• Apparel will get cheaper the longer you wait. Discounts will be merely OK until retailers fear they’ll be left holding that unwanted handbag or holiday dress. Then the real deals will appear.

SANITY. The busiest shopping days of the year are typically (in this order) Black Friday, the Saturday before Christmas, and the Saturday after Thanksgiving. If you like crowds and bustle, by all means go for it. Otherwise, stick solely to online shopping on those days. Keep in mind that crowds and pressure affect decision-making, and not in good ways.

SHIPPING. Most retailers plan to lure shoppers to their websites by providing free shipping again this year. For packages that you’re planning to mail yourself, get them to the Post Office by December 19 for cheaper First Class service or by December 21 for 1-3 day Priority Mail. By the way, the USPS has free boxes in a variety of sizes that you can stuff to the brim for a flat Priority Mail shipping fee that’s typically lower than shipping your own box via Priority Mail. No matter how you’re shipping, the longest lines at the Post Office, FedEx or UPS are likely to be the Monday after Thanksgiving and the first two Mondays in December.

Oh, and no matter how you shop or when you plan to start, remember that goodwill toward others is the theme of the season!

Kit Yarrow, Ph.D., is a consumer psychologist who is obsessed with all things related to how, when and why we shop and buy. She conducts research through her professorship at Golden Gate University and shares her findings in speeches, consulting work, and her books, Decoding the New Consumer Mind and Gen BuY.

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