DH and I been together 5 years. Married in November. I came off the injection (depo provera) in February, as in my shot was due then and I didn't have it. Didn't have any periods while on it, and was on it about a year and a half.
Obviously with everything that's happened we're holding of on TTC at the moment, although if it happened it happened.
I've bought ovulation sticks and am still not ovulating, 3 months later. 
Everyone I've spoken to said it's taken them at least a year to conceive after this. (I know I'm fertile, or at least was, before going on injection, DH also has 3 kids from previous relationship)
If anyone has been on it and can give me a timescale of how long it took for them, just for my own information, I'd be truly grateful!