Worst case is around 18 hours of warning. Kimmel would sortie, likely lose one or two heavies to the IJN submarine picket line, and get caught in the open sea by overwhelming Japanese airpower. There is also the potential for at least Enterprise to come roaring back from the ferry mission to Wake and collect a torpedo or three from the picket and the outside change of her being found and sunk by the Kido Butai.
Casualties in this scenario would soar, and the ship losses would be actual losses, not refits (which most of the BB at Pearl needed in any case).
I tend to disagree with the potential for a 3rd strike being that crippling. Dry docks and repair shops are surprisingly resilient. One of the striking photos from the raid shows Dry Dock One on the aftermath of the attack. The two destroyers in the dock are wrecked and the USS Pennsylvania was ht by both bombs and parts of the destroyers (including a 1,000 pound torpedo mount). The one way to damage the dock seriously was to torpedo the caission, something that the Japanese attempted in the first wave, all of those efforts failed.
As as demonstrated during the Combined Bomber Offensive machine tools are really hard to destroy. Buildings are one thing, the tools themselves are much less likely to be destroyed. working without full enclosure is much less of an issue in Hawaii than would be the case in a cold weather location.
A third wave would also be forced to deal with the very heavy smoke that was coming from the ships in the harbor, something that would be vastly increased if, as is generally proposed, the tank farm was attacked. Each tank was separately protected by earthen berms, only a direct hit from either a dive bomber or high level bomber would be sufficient to set fire to the bunker fuel, a couple tracer rounds wouldn't do it. Once a tank or two is hit the resulting smoke would obscure the target from that point forward (this is a serious issue when each aircraft has a single bomb, even more than is the case with strategic bombing with massed heavy bombers).
That third wave would also face a fully manned defense. Pearl Harbor had a very robust AAA capability, as is illustrated by the fact that, even in the madhouse of OTL's two waves, the attack waves suffered not just the usually discussed 27 aircraft lost over the target, but an additional 40-50 (figures vary) that made it back to the fleet and were pushed over the side as being beyond reasonable repair. All told, despite the absolute surprise and rather woeful readiness of American defenses (most AAA batteries had no ready ammunition stored at the mount, the ammo as locked away, in many cases it as necessary to use fire axes to get into storage lockers) 28% of IJN aircraft (101 out of 353) received damage either from AAA or from the limited number of defensive fighter that managed to launch. Any third wave would have had to refuel, rearm and return to Oahu, there would have been at least two, more likely three, hours between the departure of the 2nd wave and the arrival of a 3rd. It would have flown into a fully armed and manned defense, with around 20 P-40s and 10 P-36.
