I started Bodhi off lead when she was just a tiny puppy.
It was scary the 1st time - but at that age, she wasn't going to go anywhere except with me.
Personally, I think the earlier you do it the better for both you and dog.
I STILL work on recall constantly. She is very good, but I can bet you, if I stopped working on it, she'd stop doing it. I can even call her away from her logs - which is no mean feat!