When invoicing a client, you can choose to “Email invoice to client.”
If this option is toggled on, you'll also be presented with the option to “Email invoice later.”
Turning this on will prompt you to select a date for the invoice to go out on. The email will be automatically sent at noon (EST) on the day it is scheduled.
A few things to note:
If your due date is sooner than the delivery date, your client will see the invoice as overdue.
If you log new sessions on this engagement between the date it was created and the date it will be sent, they will not be associated with the pending invoice.