Hard to tell with nanners, much easier with complete balls (5 nanners that open within hours after the ball opened up into an umbrella). They get a little yellowish instead of green when the pollen is mature. As you can see, yours is yellow already. It's pasty before it gets powdery so removing them early gives little risk of actually spreading viable pollen in the air.
The problem is there maybe nanners you don't see until it's too late, or mature within the bud and might just pop when you pull or trim the plant. I would also factor in the amount of bud sites. A couple of colas are obviously easier to inspect than a monster crop with lots of small buds.
A possible alternative would be to put it in another room behind the window if it's just a matter of wanting the trichs to develop further. The more I look at the pic, the more it looks done though. You don't actually have to wait for amber (or even cloudy...) and looks like they finished swelling up. So I wouldn't take any risk and better be safe than sorry. It really does only take 1 nanner's pollen and some air circulation to get some seed in all buds.
