Starting birth control

So I'm getting married in August and we decided we are going to stop using condoms and use birth control pills. This is our mutual decision. I have been on birth control before, I know there's still a very small chance of getting pregnant. We agree we would rather do it this way..

Just want to throw that out there lol before any negative nancys come out

Anyhow, when I was on the pill previously it took me 3 different kinds to find one my body could handle. Unfortunately I can't get that same medicine anymore so I'm going to have to go back through that whole process again of finding me a new set of pills.

How long do I need to be on one set of pills to prevent pregnancy? Will one months dose work?

For example what if it takes me until July to find my right pill.. will I be protected on my honeymoon in August?