Birth control pill effective after a week?

I have been prescribed the birth control pill. I am taking the lowest dosage of estrogen because I am a smoker (I do not intend to quit, I am aware of the risks, and i am 24). My OBGYN told me it takes a week to be effective. Is the 98% effectiveness on its own, or only in tandem with a condom? Also, is it only a week after taking it that it works? I have heard a month, three months, or even a year for birth control pills to be effective. My doctor told me a week. I don't want to take unnecessarily risks. I do understand you can get pregnant when on the pill, but you can get pregnant when using a condom, too. I don't want to have to use o0ne during , so basically- Is the pill just as effective without a condom? Which means about 97%?