@Kathryn145, the August lock system does indeed send setup information to the guest immediately upon a confirmed booking (you will get the confirmation email from AirBnB and the August lock email around the same time.)
Your bet that the system is not smart enough to manage hours is wrong: the August lock *will* be set up automatically according to your exact chosen check-in and check-out times.
If the guest does not set up the August lock software after a few days, you will be sent a reminder email with the instructions that you can forward to the guest. I am not sure if the guest also gets a copy automatically.
For myself, I also send a reminder just before the trip with the necessary check-in information.
It does work as described.
Did you get a keypad to go along with the August lock?