J.W.
You definitely want to give the birth control time to get into your system and you want to make sure that your cycles are going the way they should before you do the deed. If you REALLY want to be sure you don't get pregnant, you may want to wait even another month. Obviously that's not ideal for a marriage so one thing you could do as a back-up is withdrawal. NOW, it's not 100% effective but with the birth control, it should ease your mind a little. I would still wait as long as you can though to be on the safe side before having sex at all but if you can't wait, that's one options. There is also always condoms which aren't the greatest, I know but it is an option. Just make sure you always use some back up method if you are ever on antibiotics because they tend to reduce the effectiveness of birth control pills. Good luck. I'm married, pregnant with number two and I know how stressful it can be when the timing "isn't right".