I just started a plant on a 12 and 12 schedule. However, last second I had to do some maintenance. The maintenance lasted over the scheduled time for it to go to darkness but I still turned off the overhead HPS. So, the HPS was off however it was still getting light from lights in the room. I'm just wondering if I should turn the light on 12 hours from the supposed time of darkness or when I was done after maintenance (about 2 hrs. later) when it went to pitch black. Thanks!
You can stick to your former schedule, but don't let this happen again. Finish your work during lights-on period, or stop at lights-off and resume some other time.