Hi windy cottage
I don't know your medical particulars. Basically, it should be reversed when the doctor thinks it is safe, no infection or inflammation, you've had ample recovery time to regain your strength, and all other medical issues stabilized.
Depending on your age, reason, diagnosis, etc, it may be anywhere from 2 months to 6 months; if it was done for cancer they will often do chemo/treatment and wait for a yearto check for recurrance.
Sorry it's not a straight answer; the question is probably best answered by your doctor.