hi you need lots of roots coming out those blocks before you flower.
did you pre soak the rookwool blocks in a5.5ph solution for an hour or so before planting the cuttings in them? that stops them turning yellow!
I hate to be the bearer of bad news but the plants don't look that healthy(u need roots) and if you have spider mite on them at this stage and especially they're webbing already I doubt you'll get to the finishing stage
you could always try these to try and combat the mite. I got mine from ebay (Red Spider Mite Control [Phytoseiulus-System] ebay item number 173279328135
I spoted the mite to late in the summer and had to clear everything out and start over again
like