Adjusting light schedule....timer failure.

Hi everybdoy...got two questiond involving lights and times. First off had a timer fail this morning on a 400w mh. It was 1.5 hrs late to start(manualy) The 1000w hps on the other side of the room did come on. So lights-on time stayed the same...just not as bright. Is this gonna cause a prob? Also...the failure was cause by a crap analogue timer....I want to switch to digital. Can I adjust the lights on time by 10 or so mins without upsetting the ladies? They are in there 4th week of flower.
Thanks in advance
have a nice day.