Hate to say this but .... Those Mars hydro panels will not grow more than one or two plants half ass. The stated " power " is false they are about 1/2 of stated power based on actual pull from wall. So you are ACTUALLY putting out about 155 each.
The panels CAN do 300 but are built to " throttle " down as to give the diodes a longer life.
I would say target a more manageable amount of plants to start - say 3 or 4 .
This way you can concentrate on them easier than trying to juggle 12.
Once you get things operating , you can start up a couple more , so on and so on.
Autos are easy , plant and go. Once they pop they cannot stop. They veg only for a short period then start throwing pistils around day 35-40 ( typical ) from seed. The breeder estimates on yield , harvest time , size is a GUIDE ONLY ... Most perform better running a bit longer until they are mature , NOT on week you are on.
Stateside :
DC Seed Exchange
Greenpoint
The Vault
and a few others ( look at seedbank reviews on RIU )
Overseas :
TSSC
I buy 90% if my autos from here - I always got my shit from them .
They take CC , and it is secure. It DOES NOT appear as a bad purchase thru card.
I have even bought with my ATM debit ... You tell bank to open card to SHOP international . It takes less than 5 min. Then you are good.
I ordered here OVER 15 times , never an issue.
They have a huge selection , both regular , autos , hybrids , premium.
Good luck