With FireText's handy scheduling tool you can schedule your message to go out whenever you want!
STEP 1: Compose your message as normal, but instead of hitting SEND select SCHEDULE FOR LATER
STEP 2: Enter the date and time of when you want the message to send. You can repeat the message to go out every X days until XX-XX-XXX by hitting the REPEAT? button if you need to
STEP 3: When you're happy hit SCHEDULE SEND
You can view your scheduled messages under the SCHEDULE tab in your account :)
Please note: you must have available messages remaining in your account for scheduled messages to be sent.