How important is air temperature to the first stag...

yeah man it will, just put it on 24/7 light cycle to maintain that perfect day time temp throughout , won't matter really until flower you'll have figured it out by then i hope😂

When the temperature is lower than 23°C (73°F) the growth slows down to a crawl. Once you get them above said value your plant will explode with growth. Try to dial down the exhaust

So theres a few things that can affect young growth and heat is one of them based on what I see in your diary logs I would raise your daytime temps to about 28 C and your night time temps to no lower then 18C . The reason I say this is because anything over 28 C starts to add heat stress depending on the strain and anything lower then 18 C at night and the root system pretty much stops uptaking nutrients and water anything lower then 15C and it will stop all together . The ideal temp for your substrate to be is slightly above 20C this way the root zone will always uptake nutrients without ever getting to hot or to cold . Its important to understand that cannabis is considered an annual which means during cold temps it will go dormant and then during the warmer temps it will pick back up and grow again . So likely with your plants being so young and your temps being so low it thinks its almost winter time and isn't growing as much . Here's a few easy methods you can use to fix these issues to have optimum growth conditions for your plants . You can try buying a heat mat and placing it under your pots this will warm up the substrate and your root zone will continue to absorb nutrients and water . You can also lower your lights start slow and increase how close your lamp is as you see needed , I say this because I don't want you to just lower your lights and then burn your plants with light burn . The last method is a bit more expensive but works well if the cold is super hard to manage , you can get yourself a little space heater but don't cheap out on it buy one that you can adjust them temps and that will shut off on its on when it reaches the desired temperature in the grow room . I hope this information serves you well on your journey to becoming a grow master !! - Happy Growing!