any help please..my timer went last night and my lights have been switched off 3n half hours extra so total of 15.5 hours dark, will this make a difference to my plant
Any schedule you like would be fine and the extra darkness won't hurt the plant or its development regardless whether it's vegging or flowering. A one time boo-boo won't affect them.
Repeated light leaks during the flowering phase is a strict no-no tho.