Hi scousa
ww is about 55 days for flowering, if i remember right lol, so you have about 5 weeks left, give or take a few. So christmas is do-able.
flush, atleast, the last 2 weeks with the same ph water you've been useing. changing it once during that process.
If those were mine, i'd add, 1/2 teaspoon of ebson salts per gallon, immediately, to my res. , but that's me.
Those buds will really fatten up and get a frosty white in the last few weeks.
If you've gone this far and this good, get a 10x- 30x magnifier to view the tricr. when 75% of them change color, their done.
My hat's off to you, great job on a first grow, hell any grow.
peace
heart