Actually, it depends on the test you're buying. Some are more sensitive to lower levels of pregnancy hormones than others.

The best, most accurate test would be a test in a clinic or doctor's office -- possibly the one you got the Depo shot from?

If that's not an option, here's a list of which over-the-counter tests will you the more accurate answer: http://babyhopes.com/pregnancy-test-sens...

its very rare that u could be pregant because yes it takes 15days to work but wat happens if u get pregnat and u take birth control alot of the time a miscarage. i have been on the shot before i hated it i was on my perid the whole time. but i would say just to be safe use the best test.. first responce it dects pregncy 5days before ur missed perid. i would test on the november 1st. pregnacy test are exspeive yes u want to know but testing to soon could only make u wonder. but if u miss ur perid i dont be to scared the birth control shot can sometime cause that but since ur almost a month after intercourse its safe u can use the cheaper ones after the novmeber 7th and if u have no perid by decemeber but u test pregncy test every two weeks by then and there all negative ur not pregnat its just the the shot that is makeing u not have a perid.

get a first response kit. my sister used them everytime because she always needed to know before the doc, as she put it, so far everyone has been right. now would be a good time.