Do It Now.

I think I've made my views on this clear in the past, but you need to go get emergency contraception. Right now. Plan B is now available as a single pill. In the past, it was necessary to take two pills, twelve hours apart. This is a great step forward (anyone who thinks having to wait 12 hours to take a second pill is no big deal has never been, or had to deal with, someone who actually needed to use EC...the condom broke, or there was an assault, or there was a night of drunken irresponsibility, or whatever; waiting 12 hours to take the second pill and 'be done with it' can seem like torture).

It's available over the counter if you're over 17; with a prescription if you're younger. Buy some for yourself, and encourage your friends to do the same. If you have a teenaged daughter, take her to the doctor for a prescription and get it filled (assuming, of course, that if she's sexually active you've already been a responsible parent and taken her to an OB/Gyn to get on the Pill, had a long talk with her about the importance of taking charge of her own sexuality, only being sexual with someone when she's ready, not when some sixteen-year-old Lancelot starts panting about 'If you really loved me...' and, for the love of all that is holy, USING PROTECTION).

Oh, and obligatory myth-busting--EC doesn't cause an 'abortion.' In fact, it won't work if you're already pregnant. So, on this particular point, right-to-lifers--chill. Also, EC is safe--safer than aspirin (though the more I learn about NSAIDs in med school, the more terrified I am by the prospect of using ibuprofen, or aspirin, or any of those ilk anyway).

When/if the need arises, you'll be glad you have it in your medicine cabinet.