Waiting till J3 is a pain, but it allows me to get more into the battle.
you end up getting blocked though which is the problem. unless you move naval over the islands you are going to take and have the boats loaded on J2.
usa tends to get everything to queensland still even if you can sink it (tend to just block with a dd or two).
no real advantage money wise waiting for j3. you lose the 10 NO. to pick up 12-13 in islands and FIC. usually -7 or -11 for allies. so usa getting his NO for the other powers to be weaker is the tradeoff.