Change flowering light times?? HELP please read!

Right now my plants light cycle for flowering is 12pm to 12am on, 12am to 12pm off.
I really want to change it to 7am to 7pm on and 7pm to 7am off.
Would that put my plant through shock?
please help!

They say: During the flowering stage, indoor plants can easily handle no light for 48 hours and even longer. They do not grow as much and get pale or wimpy, but they will survive.
And to set the time cycle I want i'd have to keep the lights off for 31 hours untill tomorrow at 7pm. Im worried since it might get pale or wimpy that would put it into shock and turn into a hermie.
What do you think?

I ment untill tomorrow at 7AM.

Instead of making the change all at once gradually move the time in the direction you want, a couple hours each day until done.