Reputation Builder will send emails based on your Communication Method either manually or automatically. Please refer to this post on How to Change the Communication Method.
In Automatic Mode, Reputation Builder will send emails the day after you upload the customer, at the following times:
6:00 am, 10:00 am, 1:00 pm, 8:00 pm and 11:00 pm PST
When uploading a new customer, you can select to send the customer a feedback request immediately, and it will be sent out right away. This will not count against your daily feedback limit when in Automatic Mode.