I started taking birth control about 2 weeks ago but I have stopped now, how long do you think its going to take before I can get pregnant? When is the best time to try to?

It could happen any time. Usually in the middle of your cycle is when you ovulate, so try then. If you want you can purchase ovulation tests to help you determine when you're ovulating.

Pregnancy is not an exact science, you have to determine when you ovulate to better your chances.

Here is a link where you can determine your peak fertility window...
American Pregnancy Association : Getting Pregnant: Ovulation Calendar

When I was trying to get pregnant me and my boyfriend did it every other day.. I rember someone on here give me the advice it was better to try and so it like that so that there is constantly sperm in the body rather than trying to guess when I was ovulating.. and let me tell you it worked for me, I am now nearly 9 weeks pregnant... good luck