Welcome to BYC! I think she'll wait but for how long is the question...she's going to have to take the early chick(s) to eat and drink. I had a broody keep sitting on the last egg after three had hatched. After 2 days tho, she finally left the egg. It was pipping so I brought it indoors and hatched it using a heating pad.
Good luck with yours, keep us updated!
She ended up hatching 2. The first hatched on the correct day. The other hatched 6 days later. We didn't think any others would hatch because she didn't lay on them for 2 days but she's a miracle chick.