wait(20)
20 seconds.
Boom.
Magic.
Then add all your functions and conditions to make them fall... AKA just unanchor them all and they all come falling down.
@op
*facepalm*
local plates = {get to all your plates}
do
wait(20)
plates.Transparency = 1
plates.CanCollide = false
wait(1)
plates.Transparency = 0
plates.CanCollide = true
end