(Going of memory)...
You have 30 days from the time pictures are taken to "claim" them in your account. So anything taken on 2/13, needs to be claimed by 3/13.
You have 30 days once you claim the pictures to place your order. So you'd need to place your order by 4/13.
BUT, again IIRC, you can also pay for a one to two week 'extension'. If you do that, you should be good. The extension would be cheaper than a second PP order. Just keep in mind, you'd need to order your CD within a week of returning from the second trip.