Hi @AD10 this is a great question and important for several reasons. Guests do not receive the Airbnb check-in instructions until three days before their reservation commences.
As a professional co-host I use software to help automate much of the messaging with guests. This includes an automatic message sent upon booking confirmation, a message on the day of check in, and one the day after they have checked in. This encourages greater communication from guests - which is extra work - but also means I avoid problems, and if something does go wrong, guests are comfortable communicating with me, so I can fix the problem quickly. Good luck with your hosting! Sofia