I suggest you candle all her eggs, and remove any that do not show development. Then mark all the eggs you leave with her, and check every day or two to remove any new eggs.I know the hen that laid the egg has been sitting for quite a while now which is why I thought a hatch was imminent. When I lifted her up, she had probably a dozen eggs under her so clearly other hens have been adding to her clutch. Unfortunately there isn't really a way for me to block her off in the particular box she is in.
Then make a note somewhere, of how many eggs and how far along they appear to be, and you will have some idea of when to expect chicks.
I agree, not a good thing to try now, if you want her to continue with those eggs.I could move her to a brooder but every time I've done that in the past, the broody has abandoned the eggs.
I've had some luck moving a broody right at the beginning, and giving her fake eggs for a few days. After a few days she is either content in the new place, or has clearly quit being broody, but at least I know before there are any real eggs involved.