While I can see the reasoning in saving your money as Japan, I think that fully loading their transports is important for Japan. I like to buy three infantry on turn one. Saving your money from turn one to augment your purchase on your second turn may very well work out for you. But unless I was buying fleet or aircraft on my second turn I would buy that infantry on my first turn.
You start the game with 2 transports. Keeping those transports loaded with infantry is key to having any kind of success in mainland Asia, whether you are targeting the UK or Russia. If you can convince the US to attack you, so much the better. Germany can normally handle the UK and Russia by itself, especially if you as Japan are chewing on their IPCs.
My 2 IPCs,
-Midnight_Reaper