Usually, I will release the check-in instructions with the codes several days in advance, in case there are questions. Even then, several times, guests have not received the message - either through not checking Airbnb messaging, or not having the app on their phones while travelling.
I've had to call people who have not responded to my requests for confirming arrival times and confirming receipt of entry instructions.
I think it's unconscionable that Airbnb would release a private entry code without consulting the host - it's very lazy, at best - especially, since codes may change and it might not even work. CX is going to default to the thing that gets the issue off their plate as fast as possible, be it right, wrong or indifferent.
But I also think it's not very practical to release entry codes too short a time before arrival, without making sure the guest fully understands the check-in process.
I realize folks have automated keylock systems which release codes just before assigned check-in, but this seems like it's open to communication issues, unless one has notified the guest well in advance that codes are issued just before confirmed check-in, and received their acknowledgement back. Guests have to be responsive to messaging, and communicate changes to their travel plans so hosts know when to expect them.