Yes, input event messages usually appear before your actual input, but only on your end. They should appear normally for others. You can get around that by using a timer. Normally a timer with 0 seconds is enough, but if not, you can set it to 1 second.

Code:
on *:input:#: {
  if ($1 == !bash && $2) {
    .timer 1 0 msg $chan $nick bashes $2 with a 4Sledge hammer.
  }
}


Just replace the 0 with a 1 if 0 doesn't work for you. And, no, you cannot use the same format for on input. See /help on input . If you could, I'd have done it that way in the first place.