I want to take a moment to remind you all to wait til the last minute to Christmas shop online this year.

Wha??

Well, you can, once you have a free three-month trial membership to Amazon Prime, the service that gives you free 2-day shipping on orders of ANY size. There's a bit of a trick to getting a three-month trial instead of the more common one-month, but it's not hard. This should work for anyone who has never been a Prime paid or free member before:

1) Go to Amazon but DON'T sign up for the free 1-month trial.

2) Instead, put a $100 worth of textbooks in your cart. I used this one. Don't worry, you won't have to buy it.

3) Proceed with the check-out process. Before you get to the final purchase page, you will get an offer for a free THREE-MONTH trial.

(NOTE: Thanks to reader Brian for pointing out the exact location of the link, which you might not see right away: "the link is after you enter a credit card, and when you're finalizing your shipping options. It's kind of wedged in there among the existing shipping options, but it's definitely there.")

4) Accept it!

5) If you don't want the textbook, delete it from your cart.

And if going partway through the check-out process for a $100+ snoozefest biology book makes you nervous, remember that you can always just cancel Amazon orders before they ship at no charge, by logging into your account. It's easy.

Why you want Amazon Prime for the holidays:

I did a lot of my "Santa" shopping on Amazon last year, and enjoyed the fact that I could order the kids' gifts while they were tucked in bed, instead of trying to shop with them in tow ("Hey! Isn't that Rudolph out the window there? Clerk, could you wrap this, stat?) or wasting precious childcare hours at the mall. This year, local sales tax increases have given me even more incentive to shop online.

But I ended up paying a lot in shipping last year. I'd carefully choose several items together in order to hit the $25 minimum for free Super Saver Shipping, only to realize at the last minute that one or two of the purchases were from independent sellers and didn't qualify. Then I was faced with two choices: Stay up late searching for fillers to bring the qualifying portion of the order up to $25, or just pay shipping on the whole thing.

To be sure, the items that are ineligible for Super Saver are generally also ineligible for Amazon Prime -- stuff from indie merchants who don't use Amazon fulfillment, according to the Amazon Prime FAQ. However, I clicked around and found lots of potential gifts that do qualify. I think this will be a Godwend when I inevitably realize I need ONE MORE stocking stuffer or Secret Santa gift and the month of December is getting long in the tooth.

OK, of course you know how shipping gets during the holidays, so I'm not saying wait until the last, last minute. But still, if you do end up pushing it timewise, the promised 2-day shipping with Prime is a better bet than the regular Super Saver. Also, Prime members can upgrade to overnight shipping for $3.99 per order.

A lot of people love Amazon Prime, so maybe you'll even want to keep it after the trial, when it will cost the regular $79 a year. But if you think you WON'T want to keep it, you can also prevent that bill from hitting your credit card in three months: Log onto your Amazon account, where you will see the option of managing your Amazon Prime membership. From there, you'll be able to click a button that turns off the "auto upgrade" to the paid membership.

I signed right up for the three-month trial after reading about it on Wantnot.net. I'm excited to try it before the holidays, maybe by snapping up some grocery clearance items.

Oh, and if you don't like the idea of the textbook fake-out, you can always just sign up for a monthlong trial and do all your shopping early.

And then just hope that Christmas isn't cancelled this year due to financial apocolypse.

Disclosure: This post is riddled with affiliate links.