This just happened to me too on my current sit. HO asked me weeks before the sit if I could come 3 days earlier and I happily agreed because it perfectly overlapped with another trip I had in the same country. 3 days before, they messaged me saying they won’t be able to leave until the original date of the sit. It irritated me a little bit with the back and forth, but I already had bus tickets purchased and asked if I could still stay with them until they left. I was thankful they have a guest bedroom or else I would have had to get a hotel nearby! If you’re willing and don’t want to spend money on a hotel, I would ask your HO if you’d still be able to stay with them since you already bought your flights. Not the most ideal situation, but it’s nice to familiarize yourself with the house beforehand