At 7 a.m. (Eastern Standard Time), every player is given 4 additional visits, up to a maximum of 12 visits.*
You will also be given deliveries for all the threads you pwned since your previous delivery.*
If you need to know what time that is in your local timezone, use a time zone conversion site like this.
*Note that it takes time for the database to give thousands of visits, so it may be slightly past rollover time when you get your additional visits. Be patient!