Welcome to the forums.
From what I understand you want to add a delay to some buttons that change the frame when the mouse enters them, unless it is something else that I not getting.
This is a little example project that uses a timer so that the mouse must hover over the button for a certain amount of time before you change frames.
hoverButton2-16-2022_15-56-05.wick (2.2 KB)
In essence you can make a delay with something like this,
In the default script of a clip
this.timer = 0; // this variable will count the frames passed
Then in update, or the script in which the timer should update
this.timer++; // increment it by one per frame
if (this.timer >= 20) { // you can replace 20 with how many frames you want it to wait
gotoAndStop(2); // you can then do something like switch frames
}