How to complete this attic grow room?

I have the fans and the lights i just want to know if theres any more i could do with this space. I'm thinking about getting some mylar and stapling it to the edges, but i ran out of money, so far i've spend over $650 on this project.

water pump --- $20
attachments --- $15
Sockets and switch --- $2
fan - check
Lights - check
2 timers --- $40
hangers for the lights ---$10
Ballast and light --- $220
bubble water - check
cord for light- check
PH tester - check
fan- check
table - check
root hormone --- $8
seeds --- $180
white paint - check
scale --- $15
door closure --- $30

i'm starting with some white widow and some BC Mango seeds form the bcseedking and then theres some seeds i'v bought from the Vancouver seed bank

the light i'm running is a 4 foot florescent light for the seedling and then theres a 400watt mh light

your going to hate the plastic on the floors. you should get a piece of plywood and lay it down . then get some linoleum for easy mess cleanup.

I would but then there would not be enough room for the plants to grow. I have another question, would it be possible to start to flower my plants when there about 1-1.5ft tall? also do the plants grow in the flowering stage? and if so how much.
thanks

yea that sa botu perfect height for a small but decent size yield. but you shouldnt always judge by height, go by growth/ health ratio . yea theyll grow about another foot .

Yeah, you should usually wait until the plant is at least 18inches tall to flower them and during the flowering stage they can usually double in size

What about the Temp does it matter what temperature is when the lights are off if it doesnt go below freezing?cuz my room at night goes down to 5-10 degrees but in the after noon it can go as high as 30

make sure it doesnt go past 65 at night , if it does get a tiny heater/fan

65ºF minimum - 85ºF maximum. intake and outake fans help control grow room temperature. Insulation helps keep a stable grow room temp. (preferably an insulated box around your setup seems to be the easiest to control temperature with insulated walls painted white or with mylar inside.