Our little boy is 7 months old and is a comical enthusiastic fluff monster.
I'm not so sure that it's because he wants to be in charge, I think he is just maybe testing the boundaries, but he has always been an eager, throw himself into everything kind of doggie who is difficult to strictly discipline - not that we would want to completely, because we love his enthusiasm!
We are consistent with our boundaries and try to stay calm and steady and we guide him in his behaviour. He knows what we expect from him and what is unacceptable.
Time out is a few mins of ignoring him (which he doesn't like). What we also do is divert the unwanted behaviour into behaviour we do want, so if he is getting carried away, we distract him with a command we know he knows, like sit, paw and stay, and reward him for that behaviour instead - I have found this does calm him down when we need him to be calmer.