I figured to go ahead and prime before joint compound and finished the first bedroom a couple weeks ago. Looks good. Slight change to my steps.
1) remove all batten and strips, strip popcorn ceiling, remove/hammer all hanging staples/brads
2) joint compount all deep spaces
3) sheetrock screws all around to reinforce staples
4) replace all electrical receptacles with standard "old construction" boxes and outlets
5) clean walls and ceiling with TSP
6) prime walls (not ceiling)
7) tape and joint compound walls
joint compound on ceiling as needed (was surprised to see that ceiling taping looked good under popcorn and just needed some minor touches before paint)
9) Magic Trowel walls for smooth finish (Google Magic Trowel - great tool)
10) prime walls and ceiling
One change had to make in second bedroom. After removing batten and molding some gaps were huge (not shrinkage - poor installation). Had a full sheet of wallboard sheetrock left by home installers. Cut out and removed slightly larger sections of wallboard where the gaps were and installed new wallboard cut slightly larger to remove the gaps. Also, one two foot wide section of wallboard from ceiling to floor was previously screwed into wall in a way to easily remove for access to back of shower. Fully screwed this same sheet to studs and installed a 6" x 9" access panel for shower head and a 14" x 14" access panel for faucet and shut-off valve access. Access panels available at Home Depot (Oatey brand).