There is zero days left it says one with unix epoch time?

I'm making a live event and added a countdown so players know when it will start, But when I tested it, there were 0 days left but it says 1 day left, Can anyone help me?

Here's my code

local timeToStart = 1621196661

local timeToStop = 1621197661

function liveEvent()
	game.Lighting.TimeOfDay = 0
end

while wait(1) do
	
	local currentTime = os.time()
	
	if currentTime >= timeToStop then
		break
	end
	
	if currentTime >= timeToStart then
		print("Start the event")
		liveEvent()
		break
	else
		print(timeToStart - currentTime.." seconds left until the live event!")
		
		local day = os.date("*t", timeToStart - currentTime)["day"]
		
		local hours = os.date("*t", timeToStart - currentTime)["hour"]
		
		local mins = os.date("*t", timeToStart - currentTime)["min"]
		
		local seconds = os.date("*t", timeToStart - currentTime)["sec"]
		
		local stringToFormat = day..":"..hours..":"..mins..":"..seconds
		
		local result = os.date(stringToFormat, day, hours, mins, seconds)
		
		workspace:FindFirstChild("LiveEventCountdown"):FindFirstChild("SurfaceGui"):FindFirstChild("TextLabel").Text = result
		
	end
	
end