Poultry Talk Ontario (pto.ca)

So Peach, the only pullet from my broody hatch last August, has been sitting/sleeping in the nesting box (but no poops in it) for the last few nights but I often see her leave it during the day. Last night she hissed and fluffed her feathers at me when I wanted to check for eggs. This morning she came out for some scratch and she was very vocal which is unusual for her, but she's been away from the nest for about 20 minutes now. There are 3 eggs in it and one on my counter from yesterday morning that I've been turning. Should I let her gather a few more eggs (I've got lots for eating!) and hope she stays broody? Or are the eggs just going to be wasted at this stage?

Last time I had a broody I got eggs from a friend and just put them all under her at same time, so I'm not sure if a few days worth of eggs is Ok?

A few days worth are fine. They lay an egg each day in the nest anyway. Some lay quite a few before they set so your eggs will be fine
Good luck!

You will have to move her if you want her to bring up a successful clutch, so the other hens cant't continue to "contribute"
I personally find the best way is to mark the eggs she has now in the nest, collect any freshly laid eggs and store in the house, after 3 or 4 days when you are sure she is staying broody, take out the marked eggs and replace with your 10 or 12 saved eggs.
That way they will all hatch at the same time and there is less chance at hatching misfortunes