Spoke to my pops again about Hayward's prognosis based on information released about the injury.
Should be 6-8 months before he can start rehab. His deltoid ligaments would have ruptured with this injury and the mortise was probably damaged as well. His tibia broke in 3 places, presumably with some shearing of the bone due to the strength of the deltoid ligaments attached to the base of the tibia (the ligaments had to have ruptured for this sort of injury to occur in the first place; this dislocation literally can't happen otherwise). They'll undoubtedly use stmulus techniques to keep his quad and calf muscles from atrophying over the long period of time the leg will be immobilized, but his rehab process will be long. The expedited surgery is likely due to compound fracture or otherwise a concern about blood supply. Doctors would usually prefer to wait a few more days than this for the excess blood to leave the region to get a better picture of what's going on in terms of damage.
Big hopes Celtics fans and Godron's family need to have are (1) no osteomyelitis which is a bacterial infection affecting the bones or joint. This is what Peyton Manning had and it affected his length of recovery time, mobility and career length ultimately. (2) No frozen joint. This would likely require some fusing work and would lengthen his downtime.
Broken bones need to recover, ligaments need to heal, and his rehab needs to go well. Amount of rehab needed will be a function of the full details of the damage done, how disciplined he and his doctors are about his healing phase, and how patient he and the Celtics are about him exercising it and ultimately getting back on the court. Setbacks are easy and the best have hurt themselves trying to move too fast (Peyton). Best guess is probably back at whatever his new maximum capacity is (which may or may not be diminished) in Oct/Nov of next year. Give or take, of course.
His injury is considerably worse than someone like Lin's who simply ruptured his patellar tendon, who's injury will likely keep him out the duration of the season, but he'll be up and running shortly after he is given the thumbs up.
Pops is a practicing ER doc with active licenses in 12 states. His opinion is definitely not a hot take. He talks fast and in medical jargon so I caught as much as I could. I may have misstated something here but I think this is 99% accurate as far as his thoughts.