Try this script:

Because it is difficult to extend mIRC's toolbar (as sparta said, this requires a DLL), my script adds itself as a "Commands" menu entry. If you prefer, you can define a hotkey (F1-12) instead.
That is incredibly awesome! Omg, I wasn't expecting someone to make the whole thing laugh Thank you!!!! grin

Ok this may be too much to ask but is it possible there could be a tick box to make the timer start from now? (sending the text as soon as you click start and then waiting until the delay to send it next) - not too important but just thought it would be cool

seriously thanks a lot this is really great, I tested it and it works perfectly