I don't know when is the right time either. In my case, he makes no effort to talk to me. I assume he wants to close this chapter of his life. Which means I need to close this chapter too. I have emailed him with frivolous light comments and he responds sometimes but after I do it I feel so pathetic because it is like I am chasing after him. But you know what, if he doesn't want to reciprocate...then yes, move on with your life. Learn from your mistakes and try to do better with your life in the future. I have resolved to not call or email him again. If he emails or calls I will respond. But if that doesn't happen, then I have to know that my life is still good and will go on.
I don't have kids and we no longer live in the same state, so seeing him is not an issue. For those that do, I cannot imagine how difficult that would be.