J1 DoW doesn’t change Europe very much as the United States still needs to invest heavily in the Pacific on the first turn to have a fleet reach the action on USA3. A bit more American Pacific fleet has to be built to make up for the units sunk by the Japanese on that turn 1 attack. I always do a standard Cow opener for Japan in every out-of-the-box match, and have never regretted it except when getting diced in Yunnan. Bad luck happens.
For someone struggling to win as the Axis, I highly recommend standard Germany and Japan openings as you have the ability to follow a simple script for the first two rounds, giving a foundation for later turns. Getting income up is so crucial in the first six turns. Way too often, I see people playing scared as the Axis and focusing on defense instead of setting strategic targets to capture territories in the early game.