timer.after(seconds, fn[, opts])

timer.after(0.5, function()
	if p:connected() then
		p:chat("прошло полсекунды")
	end
end)

timer.every(seconds, fn[, opts])

local tick = timer.every(1, function()
	left = left - 1
	if left <= 0 then timer.cancel(tick) end
end)

timer.cancel(id)