Period after getting off the pill

So I've been on the pill for about 8 years.. Just got off of it 4 weeks ago so we can TTC .. I normally have 28 day cycles, so I should be starting today. So far no sign or even any symptoms (no I'm not pregnant, I wish). How long will it take to get on a regular cycle? We go on vaca next week and was hoping to not be on it but I know I'm gonna be all messed up! Thanks :)