I agree withe the previous posts. DD4.5 is pretty good at letting us know when she's not keen on something and then we just stop. Often she'll come back to it down the track. The one thing I would recommend is keeping copies, photos and videos of what your son is doing. Even now. I didn't do it nearly enough and it would have been fantastic to have had that when I needed evidence.
DeHe's story is a great example and we've had similar situations when we just though dd couldn't possibly need more and she really did. DeHe, I don't know that any of us first timers could have handled it better. So much of parenting is trial and error and even more so with these guys - especially when you have so few resources to draw from for those blurry issues where you're not sure if what's going on is a stage, a problem or aspect of personality showing through. Sounds like you were on it as quickly as you could have been!
Good luck PCm