The purpose of turning your light cycle back to 12/12 is to mimic the change of seasons,the plants tell what time of year it is by the light they see, it is a known fact that inconsistent light cycles are attributed to hermaphradites.
Once you go to 12/12 that should be it,no other cycle,if you have to you can lengthten your dark cycle one day in order to get your cycle on par with your schedule,an example would be that your lights go off at midnight then come on at noon,but that cycle isnt working with your schedule & you need the lights to come on at 4pm,you can extend that dark cycle to last till 4pm then have the lights go off at 4am ect,the main thing is consistency.
You really need a timer,in nature the daylight never gets longer,the natural change in seasons looses a minute of daylight every day,it never gains,get a good timer & keep it set.
