Exhaust fan question

Hey all
I'm trying to grow in a 2x2 cabinet and we are about to go into winter. I have a 1 week old seedling but strain unknown. Got it under a 135w actual draw from power led panel. With the light on and exhaust fan running temps are 23-27 degrees Celsius. During the 6 hours of dark I'm turning the exhaust fan off as well to keep the temp up. Any dramas doing this or should I be running the fan 24 hours. Temps with light off drop to 16-18 degrees. Planning to veg thru winter then flip when it starts warming up. Should I just go 24 hour lights on or stick with 18/6. Will post a photo when lights are back on.

Cheers

How long is winter?

I'm going to have 3 months when temps will drop to around 16 degrees when lights off

Is your space going to be big enough to handle a 3 month veg then flip to flower?

But to answer your direct question, I would put the exhaust fan on a timer or low speed to keep the air exchange going on in there.

18/6

I've got around 4 ft to play with height wise, will top and scrog so hopefully enough room ( do you top when Scrogging first). Couple of photos attached. Plant isn't looking to happy, will run exhaust fan 24hrs.

You do not have to top, can if you want. LST for sure though.