how to 12/12 automatically

I have a white widow seed but I am not around every day to deal with flowering on a 12/12 light cycle

I got a timer but its not the best and only has a timer with a switch above it with one side saying outlet on and the other saying timer on.

Is there a way I can do a 12/12 and not physically be there everyday to turn it on/off (low on money and time)