Without a loop can you tell from leaves condition

So my loop is yet to arrive
Can I tell from the leaves condition ie when they start to yellow and die off
I'm a week over breeders recommended time but I think iv still 2 weeks maby 3
What do you think
It's just the middle plant

Then check trichomes for more accurate ripeness

Really blurry pic but all white hairs needs at least 3-4 weeks.