HI Chelsea!
Use Case 1: Absolutely! One idea, you could modify your message to include a Booking field code in the message at the desired location. If you get to the booking in time, you could fill in some personalized warm-fuzzies into the Booking Field Code under the new Booking. If you don't make it in time, the regular message would send and the field code placeholder would not be included in the communication. So no harm, no foul. You can do multiple field codes in the same message... say for example, one for the first sentence and then one for the last.
Use Case 2: Yes, also possible! You could have separate Booking field code(s) for the pre-arrival message and do a similar thing. Again, the message could have most of the details needed for their stay so if you don't have a chance to personalize it using the field code(s), it could go out fine as scheduled and still be useful to the guest.
You set up custom field codes under Custom Field Definitions in Settings. If you do a custom Booking field code, you then would go under that Booking to the Custom Fields tab to define the specific info for Booking-based field codes.
Another example is, you can do Property-based custom field codes for things that are specific to that property but you might want to lessen how many email or Airbnb templates you need to build out.
Here's the support article on how to do custom field codes in messages with your guests --> Messaging - Create a pre-arrival email using email templates, triggers, and custom fields
-Shawn
