How do I make a gui disappear after a numbervalue is not changed?

Hi, I'm currently working on JAZZTRONAUTS (gmod gamemode is which pretty awesome) like-game in roblox. (most of what i'm saying you wont understand unless you know what the original game is)

when you steal a prop in the thing, the gui shows up as it changes the prop numbervalue, but i can't get it to disappear after 3 seconds without making the prop take 3 seconds to display the correct value.

this is what i had originally:

while true do
    repeat wait() until player:WaitForChild('data').propAmount.Value > 0
    script.Parent.Parent.Visible = true
    while true do
        wait()
        if player:WaitForChild('data').propAmount.Value > 1 then
            script.Parent.propAmount.Text = player.Name..' Stole '..player:WaitForChild('data').propAmount.Value..' props!'
            script.Parent.moneyGain.Text = '$'..math.floor(player:WaitForChild('data').money.Value)
        else
            script.Parent.propAmount.Text = player.Name..' Stole '..player:WaitForChild('data').propAmount.Value..' prop!'
            script.Parent.moneyGain.Text = '$'..math.floor(player:WaitForChild('data').money.Value)
        end
        local stopAmount = player:WaitForChild('data').propAmount.Value
        if stopAmount == player:WaitForChild('data').propAmount.Value then
            break
        end
    end
    player:WaitForChild('data').propAmount.Value = 0
    script.Parent.Parent.Visible = false
end

if anyone could find out how to do this correctly, it would be nice. alright, thanks.