Emmylou,
I cannot comment on the walk or physical therapy. The only situation that would limit the ability for impressions to make dentures would be his ability to tolerate the procedure. If the surgical margins are still sore, etc. it may be very painful. Other than that if healing has progressed well a skilled and caring dentist and/or prosthodontist should be able to make the required impressions to start the process.

Cheers,
Mike