Bubblegum + OG Kush Autos

NEED ADVISE: Got 8 Autos and 3 Regulars. Growing conditions seem good. Have a grow heater in a 4ft x 4ft tent, temps are fine as it's cold down my way. Soil was mixed by myself by hand and PH'd to 5.5 from coco coir with perlite. No nutrients pre mixed in the coco. The seedlings seem healthy but growing slow. Not sure if it's the medium, but been PH'ing my water to around 6.0 to 6.5 and giving a 1/10 dose of very weak nutrients beggining now at the end of week 1. Been watering with a spray bottle and occasionallly a syringe. Trying not to disturb the roots too much as I've chosen to veg/finish them from seed in 5 gallon fabric pots. The plants seem to be growing very slow compared to what I'm used to. I'm guessing it's the choice of pot size, but I'm hoping they will form a stronger root base and shoot up in the next few weeks so I can LST. I've also been using a water res tank, Ph to 6.5 and airated using an air pump with low level nutes at 24 Celcius to get it absorbed better into the medium. Feel like the leaves have been getting slightly greener after adding the nutes to watering. Feel like the progress for 9 days growth from seed they could be a bit bigger/faster. They did stretch a bit and added more medium to stabilise the stem. Any ADVISE to get these girls thriving? Could I just feed water PhD to 6.5 only until bigger? Change the LED dimmer to 100 blue and 40 red spectrum instead of 60/30 to swing into full veg spectrum early? Should I not be adding any nutes till week 2? Also trying just to water around the seedling and not the whole medium. At this stage I'm guessing around week 4 they will hopefully get some growth happening and fill out the tent.