I don’t see a reason to expose your fleet early as Japan. That said, even playing games with the Americans, albeit fun; is counterproductive.
You don’t gain much as you can still bait the US into buy full Pacific early in the game against a well-versed player, so that school of thought is out.
Carolines don’t come into play until much later in the game (read securing Calcutta) and VC win is Hawaii or Sydney. However, I’m banking that Hawaii is “easier” to take once removing the fleet than Sydney. This is primarily due to the Minor IC being able to put out multiple units round after round until you arrive with an Amphib that requires the Carolines.
Its much easier to go after Hawaii as it is a single move from Tokyo anyways (barring any blocks). Having to fight for the Carolines and then Sydney seems less… efficient?