Some people say that there are no real differance between 24/7 and 18/6. They are both acceptable veg cycles. It will not harm your plant at all if you switch it to 18/6. The plant will still be getting all of the light that it needs to grow up healthy, plus in 18/6 not only do you save on electricity, but the plant has a chance to take a break from the relentless lights that have been pouring down on them all day.

Hope this helps, and finds you well.

Peace