How Do I Make Something Appear At A Certain Time??

Okay, so about the light flickering stuff.

Create a part and insert a pointlight in it, name the part; "Light"

Create another part on the other side of the rail track, name it RayPart

Create a serverscript in serverscriptservice

local LightPart = game.Workspace.Light
local RayPart = game.Workspace.RayPart

OriginalRange = LightPart.PointLight.Range

local myfirstray = Ray.new(LightPart.Position, LightPart.Position - RayPart.Position.Unit*500) -- creates a ray from the light to the part

local PartsToIgnore = {} -- the parts you want to ignore

while wait(0.1) do
	local hit, pos = workspace:FindPartOnRayWithIgnoreList(myfirstray, PartsToIgnore)
	
	if hit and hit.Name == "Coaster" then
		print("The coaster arrived!")
		LightPart.PointLight.Range = 0
		wait(0.2)
		LightPart.PointLight.Range = OriginalRange
	end
end