Hi there,
Birth control pills leave your system as soon as you stop taking them. I would recommend on waiting until the end of a pack, because if you stop in the middle you may have breakthrough bleeding and it may be harder to predict your next period. Some doctors recommend waiting until after you have your first period once you are off the pill, but that is only because that makes it easier to predict how far along you are. (If you get pregnant your first month off the pill, you will have no guide line as to when you ovulated, it could have been the week after or it could have been 5 weeks after). But other than that, there is no reason to wait any longer.
Unfortunately, there is no way anyone can tell you when you will get your next period back! It could continue normally, and happen 28 days later, or you could be a few months waiting for it to show up. (If it takes any longer than 6 months to return then check with your doctor). I recently came off my pills a few months ago, and luckily my period returned around 32 days later (a bit longer for me, as before the pill I used to have 28 day cycles, but now it seems to have changed to around 31/32 days).
Good luck ! I hope your cycle returns normally for you !!