Do you mean to repeat a message every 15 minutes? If so try
on *:text:COMMAND HERE:#:{ if ($nick == YOURNAMEHERE) .timer (Number of times message is stated) (interval in which statement is repeated(seconds) msg $chan MESSAGE HERE }
Try this:
on *:text:!ctt:#:{ if($nick == YourNameHere) .timer 99999999999 900 msg $chan Be sure to click this link to post to your friends on twitter and help grow the channel! It's Much appreciated! http://ctt.ec/adc2V
}