I take ativan every 12 hours, im being switched from norco to oxycodone. how long do i have to space ativan and oxycodone apart?

Try holding Ativan: till done with the Oxycodone, if not feasible, a 6-hour interval would be fine, however you haven't mentioned the dosages you are on. Norco and Oxycodone are almost the same , your doctor/pharmacist would help you better as both are scheduled drugs and should be closely monitored, they do interact and can cause CNS and respiratory depression,so be cautious,lowest effective should be used if needed