You may well have agreed to show attitude when partner leads the Queen.
But is this the most useful piece of information to give partner in this situation?
Look at it from partner’s perspective.
Declarer will play the King if she holds it.
When declarer plays low from dummy she holds either Kxx or xxx
If declarer holds Kxx, this will become apparent when it is played on the first trick.
If declarer holds xxx, partner will know you hold the King from the play to the first trick
In this situation, an attitude signal is superfluous.
Give a COUNT OR SUIT PREFERENCE SIGNAL (BY AGREEMENT) rather than an attitude signal.
Of course if declarer plays the Ace from dummy, you must give an ATTITUDE SIGNAL because the position of the King has not been revealed.