It is well established in canon that Jean-Luc Picard assumed command of the USS Stargazer in 2433, being one of the youngest captains in history, only six years out of the Academy. He commanded her for 22 years until it was lost in 2455 at the Battle of Maxia. He is given command of the USS Enterprise in 2464.
I have not been able to locate any canon material as to what he was doing for the intervening 9 years. It seems he was not in command of another ship as no such vessel was ever mentioned, nor has another major post been mentioned. It also seems like it would be an unlikely decision to hand the flagship to an officer who's been on leave for nearly a decade.
What was Picard doing between 2455 and 2464?
Obviously, canon is prefered if it exists.