I waited just under a year, and a busy, drinking through a fire-hose 10 months it was!
I had originally intended to wait until my year in the East was over before joining any other bodies, however, the Royal Arch Chapter that meets in our Lodge building (and the majority of who's officers are PMs of my Lodge) made me an offer I couldn't refuse! They have planned a trip to the George Washington Masonic Memorial in Virginia for September, where they will be conferring the Royal Arch Degree. Apparently many hoops had to be jumped through to get the RWGHP and the RWGMof PA to ok this, so it is a rare opportunity.
I would be certain you have a good understanding of the Blue Lodge and are and will stay consistently involved there before seeking out other bodies to join.