How quickly do birth control pills work?

1.I just started taking birth contol pills, so I'm still in the first package, just starting week four. I am sexually active with my boyfriend, and was just wondering if the birth control pills are effective in the first package, or if it takes a few sets of pills to really work.
2.I started taking Yasmin 28 birth control pills a couple of days ago, and I was wondering if anyone knows how long it takes for it to be effective? I would like to have the option of having sex without a condom with my boyfriend, but without any unwanted surprises.

when i got birth control they said 7 days but i've also heard it can take up to a month or three to work. i waited the 7 days and now i'm at the end of my 3rd month of bc and everything's good.

It only takes about a week for most birth controls. Although, yours may be different. Just check the instructions and see how long it takes. It should say "you need to use a back up contraception for (this long)"Just check the booklet, and you should be fine if you wait as long as the booklet says.

Depends on the brand of birth control you're taking. Your best bet would be to do a search on the web and find the pills website. That would give you a more accurate time table.

It varies depending on th ebrand of pill you have, if you read the leaflet inside the pack it shoudl explain how long to wait.