I know a PanMass Challenge rider that had a total hip done last February. He started on a stationary in late March, and was able to ride the first day of PMC the first week-end in August. He did just do the 80 mile route. He was very careful starting out with outdoor riding, I think he waited until May. At first he rode a step-through frame. The big thing is to be sure you don't fall.
February might be a little early, ask your ortho.