3 months is one of the first turning points. I got back with my wife after she was gone for 3 months but I wasn't completely NC (it wasn't practical at the time), I did a lot of divorce busting stuff listed in my thread.
6 months is a better turn around point, they need distance and believe it or not, 3 months is not that long. After 3 months you might try temperature taking with a contact that is business like such as asking for something back, giving something back, or asking a non-personal question and see if they follow up with something more. If they don't then wait until the 6 month mark and try again.
I say this because that happen to me. I was in a 4 year relationship and she dumped me so after the first month of trying to talk her out of it I went NC. I did it not to get her back (didn't think it was an option), it was just to cut her from my life so I can find someone else and I did (my soon to be ex-wife). At about 6 months of NC I found some stuff of my ex's so I put it in a box and dropped it off at her door with no note or anything. She emailed me thanking me and started talking to me. She ended up asking me out but I declined. She did not take that well.
In hindsight, I wonder now if I should have dumped my "wife" and went back to my ex seeing how things turned out.