Several friends of mine have been on Depo and didn't stop bleeding the whole time they were on it. My doctor no longer even offers the shot, due to the large number of issues they saw with severe bleeding and infertility afterwards. So if you are anticipating the shot to Poof, make your periods go away, you may be disappointed.
Well....the Depo shot, for some women it can cause an excessive amount of bleeding before it really starts to work. Some have bleeding for months on end, and some have no bleeding whatsoever. So I am unable to tell you when the shot should start working for your body. But I can tell you the depo shot is a bad choice for bc. It can stay in your system (after you get your last shot, when you deceide you dont need it) for up to a year and as well as the side affects (such as horrible weight gain, irregular bleeding).