I am 2.5 weeks post op (full hysterectomy except right ovary) - how long do i have to wait to have an orgasm without penetration?

Depends: Have you had a routine 2 week post operative check? If everything was normal at that visit then you can have an orgasm. Typically, doctors like to examine you 2 weeks after surgery to check for any problems (fevers, signs of infection). For a major surgery like you had, I usually recommend waiting 4 weeks before penetration intercourse. Masturbation/orgasm is fine now if you have no problems.