Found this for you:
"When does Depo-Provera become effective?
Contraceptive effectiveness is achieved within 24 hours of receiving Depo-Provera. Depo-Provera should be administered during the first five days of a normal menstrual cycle (in order to avoid inadvertent administration during pregnancy) and/or immediately following pregnancy termination. Depo-Provera may also be administered at any time, and with no added precautions if the woman is currently on the combined oral contraceptive pill or the progestin only pill and is definitely not pregnant. "
I will tell you that spotting and irregular bleeding is not at all uncommon during treatment with Depo.
If you believe you are having pregnancy symptoms, the best thing to do is get a blood pregnancy test.
The way my doc explained it to me when i was on depo was that it tricks your body into thinking your pregnant. When i first started it i had some preg. sympt. I wouldn't worry too much about it
This is my first posting, but I really wanted to respond.
Every woman has a different reaction to Depo. After a miscarriage 5 years ago, I received the Depo shot and pretty much had spotting for a month. I also had some pregnancy symptoms. I agree that the best way to know for sure is a blood test. However, just remember that Depo effects different women different ways.
I hope this was a good post.
Thanks for the forum.