Light cycle help

I have two plants currently on the 18/6 light cycle, I would like to move the six hours of darkness back a few hours so i can have the lights off while im working and on while im at home. Can I just set my timer for the next time i want the lights to shut off or will that stress the plants too much because their light cycle was cut short?

i think you could just leave the light on until you wanted it to be off at the new time without much affect however, i may be wrong but iv read a few posts like this and they did it no problem

its not a big problem in Veg, as long as you make the light hrs longer .. and not shorter (then 12)

tho if you really want to avoid to stress it in anyway and you have time, move it a hour a day ..

Thanks man