First Time Using Birth Control

Hey guys, I am supposed to start birth control this Sunday but it is a sample birth control that I will be taking for 3 months to see if it is the right one for me. (This is for my ovarian cysts and to prevent pregnancy) I just wanted to know when would it be safe to have unprotected sex? I do not know how long I am supposed to wait for it to become effective, and also my boyfriend and I both took tests and neither of us have any STD’s or anything just to be clear.