Most Helpful Guy
It really depends on what you need. What's best for you? There's no magic number for the amount of time you need.
About 2 years ago my girlfriend of 5 years left me. I was saving up for a ring when she lost her job, didn't bother to get a new one and then left me when I couldn't afford to keep paying the bills in our apartment, but that's a whole 'nother can of worms.
About 3 months after that I met my current girlfriend on Christmas eve.. I had no intention of dating her, I just needed someone to talk to so I signed up on a random internet dating site. I ended up talking to her until Christmas morning about what had happened and she helped me deal with everything. A few months later I realized that we were much more than friends and we've been together ever since. I'm actually moving into a place with her after Thanksgiving.
The point of that rambling story is that you never know what's going to happen. There's always hope. Just do what you need to do to be happy with yourself and love will fall into your lap. It might be 3 years, or it might be next week.