How long should it take for a pinched nerve to heal after the pressure is off?

May not: If compression was very long standing return of sensation to normal may not occur.

Depends: This depends on the type of nerve, how long and severe the compression was as well as the underlying "health" of the nerve-the age of the person, is diabetes involved, a vitamin deficiency, a prior injury to that nerve, toxic exposure- all play a role in the prognosis or ability of the nerve to "heal" over time.