Indoor growers will want to switch the lights to 12/12 and this is probably your last chance to dramatically move the light schedule around. When I say that I mean: maybe your veg lights come on at 6pm. But it’s perfectly OK to switch the lights on time to 6am when moving over to flowering. Electricity rates are sometimes lower during the night, so having the lights on then could save you money. Also, consider that your house is usually hotter during the day and if temperatures have been getting too hot, have the lights on at night instead.
Sometimes, it’s necessary to visit your plants when the lights are off. If I have to, I just use barely enough light for me to see and make it quick. This is a risk that I’m comfortable taking, mostly because I’ve messed up in the past and exposed flowering plants to way more light and I feel it never really caused a problem. *knock on wood*
When growing outside, your plants will naturally switch to flowering once the days start getting pretty short. Outdoor growers still need to worry about light leaks at night. No matter how bright the moon and stars might be on a clear night you’ll never have to worry about it being too much. However, be on the lookout for porch lights, street lights, just man-made lights, as not only can they prevent a cannabis plant from flowering they can even revert her back into veg.