I don't know which idiots downvoted you but when a company esp. one the size of apple gives a 3-4 weeks shipment timeframe they should at the very least charge you for AppleCare and other services a week before they ship. They have your money now and they can get interest on it, 3 weeks in business with someone else's money at hand is ages... They are wrong and you should press he point that unless you are a few days close to shipping I find it unacceptable for you to charge me for services that based on owning a device that I (you) don't at the moment own.
AppleCare is insurance extra warranty for a device. This should be charged a upon reception of the device. What is apple insuring at the moment? A device they haven't shipped. What if god forbid a fire goes off in their manufacturing plant and they can't ship the mac? They ll credit you AppleCare back of course, but will they pay interest rates on it? Of course they won't. The boys here might not get this, but if I can have close to a month more with someone else's money, say $300, multiplied by say 100,000 buyers that's a month of $30,000,000 at hand for my cash flow and interest rates. That's A LOT of money to have at hand for a month extra, it's close to enough interest rates to pay for AppleCare itself.
If you're worried about interest on money, then the bigger idiot is the person who buys Apple Care at the time of purchase. The buyer can and should wait until the end of their first year of ownership before purchasing it.
Apple doesn't have your money for 3 weeks, they have it for 1 full year because you bought it too early! Again, you have a full year to purchase Apple Care, so your interests on money is a ridiculous argument and only proves you don't know what you're talking about. If you want to make interest on your money, don't buy AppleCare until the last moment.
As an aside, Apple will send you an email reminder that your 1-year of ownership is ending and to extend an offer to purchase AppleCare before it's too late.
I swear, if Apple were to change its policy that AppleCare must be bought at the time of purchase, these would be the same people to complain.