My looped script stops working correctly the first time. How to make a script loop correctly?

Hello. I tried making my own looped script for an animation.

What I'm trying to accomplish is, I have an NPC, and I want it to have an animation that plays and stops for a certain amount of seconds, and then play the animation, stop, wait, and repeat. Here is my script and I'll explain what it should do, or what I think it's doing (first time making my own script)

It's a script in the NPC, and there is an animation in the script too.

repeat
    while true do
        local animation = script:WaitForChild('Animation') --finding the animation
        local humanoid = script.Parent:WaitForChild('Humanoid') --finding humanoid of the npc
        local dance = humanoid:LoadAnimation(animation) --loading animation
        dance:Play() --plays
        wait(20) --I put it to 20 since that's how long the animation is, if I put it to 1 it stops the animation at 1 second and if I put it to 25 it will play the whole animation and loop it for another 5 seconds, which I don't want it looping
        dance:Stop() --stops the animation after the 20 seconds
        print("yeah done") --just checking to make sure the above works
        wait(5) --now this is the amount of time I want the script to wait until repeating and playing the animation
    end
until
print("yeah im looping") --im not sure what I was doing here but this doesn't show up in output for some reason
wait(0.5)

My problem here is, it works perfectly for the first time, but by the second loop, suddenly the wait time is off, and the animation likes to kind of just, play for 5 seconds restart and play again.

Here's the script again without the -- for easier reading.

repeat
    while true do
        local animation = script:WaitForChild('Animation')
        local humanoid = script.Parent:WaitForChild('Humanoid')
        local dance = humanoid:LoadAnimation(animation)
        dance:Play()
        wait(20)
        dance:Stop()
        print("yeah done")
        wait(5)
    end
until
print("yeah im looping")
wait(0.5)

Anyone know why this is happening and how I can fix it?