As described in the article about the emails to the client and/or driver, the rental type on a contract determines whether or not a reminder email will be sent to the client and/or driver on that contract. If a reminder email is sent, it will be sent by default the day before the scheduled departure at around 6:00 PM. 

However, you can determine this moment yourself at the rental type level thanks to the settings "Number of days in advance" and "Minimum number of days between reservation and departure":

• The setting "Number of days in advance" determines how many days before the scheduled departure a reminder email should be sent.
• By using the setting "Minimum number of days between reservation and departure", you can prevent the sending of a reminder email if the reservation date is too close to the scheduled departure date.

The reminder email will always be sent around 6:00 PM on the date determined by the above settings.

An example for clarification:

In this example, the reminder email will be sent 5 days before the scheduled departure, unless the reservation was made less than a week before the scheduled departure.