B+W transition to colour for staggered entry videos

Hi folks

Virtual choir project -
At beginning of video I have 16 videos with a staggered entrance.
Wanting to start in black and white and increase saturation to 60% (then a flash of black and before everyone is in in full colour)

Preference is to have a synchronised fade in to colour despite videos staggered entry.

From what I can see I need to use keyframes to change from B+W to colour, so this means with a staggered entry I'm going to have to estimate what saturation videos 1 & 2 are for when video 3 enters and so on.

Is there a blanket way to do this over the 16 videos so its all nice and synchronised?

Many thanks.

So I'm thinking the only way I can achieve this is by calculating back from the point I want them to be at 60% saturation.

So work out each persons entry relative to the start of change from black and white, and then calculate what percent of 60% they should each be then at to achieve the end goal.

I still can't help but think there must be a way in DR to achieve this for staggered entry videos.

You are looking for adjustment clip if I understand your needs. It allows adding an effect, in your case saturation change, to everything under it.