Pre flower trimming

Plants are showing pistils but no flower tops yet. Should I trim or just let them go?

I'd thing out the lower stuff so there's good air circulation.
Looks good

I agree with Hugo.
My pre-flowering routine is to trim up the bottom of the plant and then take at least the first two nodes off of each branch closest to the stem. And if a branch seems like to too crowded, I’ll remove every other node going up a branch.
Thats what I do, works for me!