I dig that digi temp gauge! Your little babies look amazing, just have patience and they will grow HUGE haha you'll see. Make sure to check around and do your studying, i know there is a great grow guide for beginners in the newbie section (I know because I've read it over multiple times..haha) and all over the internet. I don't recall if you mentioned so I'll ask anyways, but did you order quality seeds or just found some random bag seeds? Hopefully these ones are all female so after you harvest you can make some money to get better lights, maybe hydroponics, and genuine seeds!
Here are some links for some great guides that I strongly suggest you read and get familiar with...
https://www.rollitup.org/newbie-central/937-how-grow-marijuana.html
and
Cannabis Growing Guide
Also I'd say keep your temp around 75-80 and have that fan going gently on the plants to help promote strength and growth in the stems... the fan will simulate the wind like the outdoors.
Are you getting fresh air into that little space? If thats a closet you should open the door at night or leave it a bit open, and maybe set up another fan to blow out the stale air and have another fan blowing air on the plants like I said earlier.
Just a thought I noticed from your pictures...look into constructing a makeshift "hood" for those lights on the Y connectors so all the light reflects back down onto the plants... so you use all the light you possibly can and that will definitely make your plants happy!
Oh yeah and like someone else had mentioned, don't use miracle grow... research around the internet or local stores like fredmeyer, shopko, etc.. for some better nutes (you'll learn allll about it after reading those guides!)
Last but not least, good luck and keep this thread posted with good pictures I can't wait to see what is about to happen to them!!