It would be great to have a time field with what hour/minute to trigger an email to guests. We have found that guests see emails when they are sent mid-morning or mid-afternoon. In our old system we discovered that sending emails at a specific time of day had an impact on guests seeing/reading emails.
Also, in the Triggers field "Booking has Arrived" and "Booking has Departed" are ambiguous and a bit confusing. It would be better to use "Check-In Time" and "Check-Out Time" as they are more descriptive and universally understood.
This is a longstanding and well-known need. It had been our hope to add this capability later this year, but right now we are having to emphasize immediate functions that help our clients deal with the current chaos in the vacation rental business. It's still a high-priority feature though, and will certainly be done at some point.