Wow, glad to hear your workplace has improved so much (yes I'm a comment stalker lol) About the other thing well, as has been said before me, sounds like you're not comfortable with the idea just yet, and definitely do what feels best for you. If that's putting off moving in together, than that's the way it must be, and he should accept that. Also he needs to address his son's feelings in the situation, before any serious talk of moving in even takes place again.
I can't talk much about time frames, as the last person I lived with, we moved in after only knowing each other 6 months lol. My daughter wasn't happy with him either, but at least she admitted part of that was holding onto hope her dad and I would get back together.