I agree that the reservation number is RN-113,16x,xxx. Considering that the 'offset' between posted RN's and the actual order rate is constant:
Which offset was caused by the order system overload technical difficulties in the first couple of hours, resulting in duplicate orders and cancellation - that offset has not grown over the several days of time-span that Elon disclosed Cybertruck order levels.
The first reported order number was RN-112,745,000 about 5 minutes into the order process. The "offset" in the graph above is 30,000 ± 1,000, which means:
113,160,000 - 112,745,000 - 30,000 = 385,000 Cybertruck pre-orders on 2019/12/12
With better than ±5k units of statistical confidence I believe. Even with a slower new order rate we should hit 400k Cybertruck pre-orders within a couple of days I believe.