This is assuming you have the day, or at least the afternoon, off at home. Fire the cooker for a temp of 275-300. Put the Butt on and take it to a temp of 165IT. Once there, wrap in foil and place back on to the cooker. At that point put the ribs on, and cook until they either pass the bend test or probe toothpick tender between the bones. Should be around 3 hours for babybacks rocking at 275-300. Cook the butt until it probes tender, usually around an IT of 195-200. Depending on the size of the butt, you should have all the meat done within a 4 to 6 hour window.
Good luck, and happy birthday!!
18" OTS, 22" OTG, SJ Silver, Cimarron Offset, Coleman Bullet, PBC, UDS, QMaster ATC