How long does it take the plant to notice Lights on?? Timer fail xD

Hi,

basically both my digital and electronic timer seems to have broke and whemn i was testing my new one with another appliance i forgot to set the time back to thr correct time so when i plugged in my light to the timer and into the socket, it came on. So i unplugged it straight away. I assume that the plants dont instantly notice light like we do but i have to know for sure.

Also this was in the correction phase of my previous fail where my light stayed on an extra 4 hours on 12/12 and i heard to ensure 12 hours dark is achieved before i put the lights back on.

I have tried to search for the answer but its a tricky one to word correctly but my question is how long does it take for the plants to know its light,

will 1 instantaneous light leak or like my situation, (the light came on) effect the plants Dark cycle.

Thanks.

1 little mess up will not screw up the grow, your all good homey

not just once but long and/or frequent disturbances will cause reveg or possibly hermies