If the two Ocean Navy happens as historical that's the date that makes sense.Well, France and Great Britain can size or keep both Corsica and Sardinia in the fall of 1940 but they won't be able to hold them past spring 1941 - because of massive German and Italian airpower too close from the two islands (South East France and the entire italian coast).
FFO did a thorough analysis about FIC impacting the Pearl Harbour decision (for the reason Carl mentionned). They finally decided to stay with the same day as infamy as OTL, December 7 1941. I'll try to find the debate and reason why. It is not a case of "let's stay close from OTL despite butterflies": FTL Barbarossa was pushed by 11 months, to May 17, 1942. More like the inevitability of the U.S Japanese war since 1900.
Basically Japan commisioned two carriers in August and September 1941.by the time the crew and air groups were fully assembled and trained and the ships sailed to Pearl (slowly to maximise fuel) it was 7 December 1941. Unless you are willing to go with 4 carriers Pearl Harbour happened on the earliest possible date. Well they probably could have done 5 December 1941 if they wanted to but they felt they would be more likely to achieve success attacking on a Sunday.
With the known American ships under construction (two Ocean Navy) Japan felt they needed every possible week prior to the Americans building their fleet in order to force a decisive battle and force a surrender before America built their fleet.