Depends. If you are lookig forward to build a gang for example, I'd start now. If you're not looking for competing other playets though, in events, spar, or basing, then start whenever it gets good enough for you.
Well, if you want to start out now so you can be really far ahead of players I'd recommend starting now. But if you want to wait until it's more enjoyable then just hold off. I was waiting for Zone to get better. Still not playing Zone.