can i switch flowering periods?

i have a master kush bout two weeks in to flowering and a dabney blueberry bout a week and i have the dark period from 9:30 am to 9:30 pm
i wanted to know if there is any way possible to switch the dark to 9'30pm to 9:30 am without f%cking my plants up?thanx.......

ya...when lights are supposed to come on just leave them off until u want them to come on....it shouldn't stress that much....just dont make a habit of it.