Yes, you can. It's possible to schedule Alerts, News and Events.
When you select the relevant section from the 'Create Content' section of the Main Menu, you'll see a tick box at the top of the page with 'Schedule to send in the future?' beside it. Tick the box and a field appears where you can enter the date and time for which the alert should be scheduled. Use the dropdown calendar to select the date and time at which the message should be sent. Note that the date and time relate to Irish / UK date and time.
After entering the date, complete the rest of the form as you usually would.
Funky Frog searches for scheduled items every 30 minutes and your will be sent in the search that happens immediately after your scheduled time. For example, Funky Frog searches on the hour and on the half hour. If you have scheduled your item to go at 15:15, then it will be sent at 15:30. If you have scheduled it to send at 15:30, then it will be sent at 15:30.