@Linda108 Even for hosts with self-check-in, it would seem prudent to get an ETA, as many hosts only reset the door code a few minutes before check-in time to prevent guests showing up early. Even though guests should certainly respect check in times, I know many don't.
If they arrive an hour early, and find they can't get in, even though they are in the wrong, they are going to be irritated, and guests who start their stay irritated are likely to find fault with other things.
Seems better for the host to ask, in case they assume they can check in whenever it's convenient for them.