As others have told the time best to return is when you want to return, not when compelled or overwhelmed by the sensation or thought that you should be. Instead it should be a desire, a want, an egging, growing experience where on wishes to participate again and return to the endeavor because it has personal value. The other component I would say to this is, is that beyond question it should be something one can legitimately dedicate to or afford to do in time. There are all too many instances where people return only to drop out again because of a lack of time or another excuse. It is one thing to fail yourself in your wants, but it is another to fail multiple other people and put at jeopardy their enjoyment of something. Thus I stand by the notion that if one cannot commit to a game, thus others, they should not be doing so in the first place.
Ultimately between these two factors, I do not believe there is much if any real criteria beyond them. Everything else does not really apply in the sense that you either have the interest and the time to do so or you do not. One can always add more criteria to it, but I find that to be excessive. Review these two objectives for yourself and you have the answer you seek.