script execute at a specific ingame time?

i want to make a script that execute ween the timeofday is greater than 18:00:00 and stops at 08:00:00 timeofday but i did not know how to do it:( someone plz tell me how:) Edit: i have a problem i need to disable a script that runs only ween player joins:

game:GetService("Players").PlayerAdded:connect(function(player)
    while true do
        wait(5)
        lessons=math.random(1,5)
            if lessons == 1 then
            --swimming
            game:WaitForChild("ServerStorage").Lessons:clone().Parent = player.PlayerGui
            player.PlayerGuiLessons.Swimming.Visible = true
        wait(60)    
        end
    end
end)