Guest arriving later, wants discount

So we have a six week booking and the guest was supposed to arrive 2am tomorrow, no problem we count today in the booking, now her flight is delayed and she will arrive 8pm tomorrow and asked to change the start date. I told her no as I have had this booking for a couple of months and it's not my issue. She hasn't pushed back but I want to see what others may do or have done in a similar situation