Broody hen question that I can't seem to find a definite answer to about adding more eggs over a few days?

How many days can you/should you let a broody hen accumulate eggs to hatch? We have one that just started showing signs (after having just been inconveniently broody a few months ago when it was too cold lol) and I want to give her a chance this time! I took yesterday's eggs because I wasn't positive if she would stay in the nesting box, but she's in there again today and pancaking/being protective. We have 4 hens so I'm thinking about giving her whatever eggs are laid through the next 3 days for around 12 total, and then potentially taking her out with those to put in in a protected part of their habitat.

Soooo... Does that sound right? I would assume if you had one broody hen, duck, turkey, whatever, on their own that days of laying go by before the true "lockdown" incubation begins. I can't seem to find the right way to Google this to find out how the 21ish day window is affected in this scenario and I just wanna successfully be a chicken grandma!