After your home has been successfully booked by vacation rental guests, the next step is likely a series of message exchanges finalizing the logistics of their arrival.
Many guests will request a certain arrival time, which can be highly variable. Some guests may want to check-in early in the morning so they have an extra day of exploration or some may need to check-in at midnight due to their late flight arrival.
In either case, being present to receive your guests versus leaving them a key is something that depends on a number of factors. Of course, it is generally more ideal to greet your guests in person, but that all depends on your availability and willingness to deal with this small hassle.