I was on depo shot for 3-4 years I waited a month just to be safe lol, but I never had a problem when I took antibiotics, (I only got pregnant because I stop the shot 4 months later I'm here lol)
You should wait at least two weeks and yes it can effect it, even grapefruit juice can effect it. Ask yoyr doctor to be sure how long to wait, some antibiotics are stronger than others.
I don't think anti biotics are supposed to effect it . But ask your doctor of pharmacist they will be able to tell you a definate answer