Sleep Study retest

Question for those of you a little bit out....or further out.  If you had a sleep study prior to surgery that required you to use a CPAP machine, when did you go back to be retested post-operatively?  I haven't used mine since shortly after surgery because the levels were too high anymore.  I know I should be retested to make sure that I don't need the machine vs. just having the levels lowered.  How long should I wait to do this?

Funny I need to be retested too!  I'm due to go back in August for a 1 year check up with
the pulminary Dr. -  I'm going to ask for another sleep study as much as I hate to go thru
that again.  I do know I don't  snore anymore.

My sleep doctor told me I needed to be retested 6 months after surgery.  He said generally people can give up the CPAP by then.