How long do I have to wait to have arthroscopy of the hip after getting a cortisone shot in that joint? Do I have to wait to get it out of body?

No . If the injection helped tell your surgeon( not sure if it was in the hip joint or hip bursa)... Either way if injection helped than arthroscopy may help( for bursectomy or hip labral tear). The steroid injection may have been a diagnostic and / or therapeutic injection but does not affect ( by itself) timing for surgery... Good luck!