New pics of flower, yellow leaves

so here are some more pics of the flowering process. I have a few questions. on one of the plants many of the leaves are turning yellow. i was just wondering why they might be doing this and if i can do anything about it. i was also wondering how miuch longer they might take before i can harvest. im new to this.

mine are doing it to, i heard it just happens during flowering?

Heres a closer picture. almost 2 weeks into flowering. how much longggerrr!!!

awhile. my buds look almost esactly like that. where do you live

first of all, u'll need to know when they started flowering, and what strain your growing?
Then, you can pin point how much longer. Mostly indica take 8 weeks from start of flowering till the end. It appears you are growing indica from the large leaves. Also, yellowing of leaves can be 1 of 2 things, light and or nitro! You also need to switch to a blooming fertilizer. The 20-20-20 is good during vegetation. You'll need more of a 1-50-1 or something of that ration, high in phos..... stop the 20-20-20 NOW! Get more phos, in plants diet....