Steps to get into HBS/GSB?

I'm a non-diversity candidate (asian/white, male, straight), A2 at top EB M&A group (EVC/CVP/MOE), went to semi-target state school (Mich/UVA/UCB), finance major, GPA 3.8+, compelling and differentiated story for "why MBA?"

When should I apply as a current A2, is there anything else I should do to add to my resume (non-profit, volunteer work, start-up, etc.) and what GMAT score should I aim for to have a fair shot at getting in?

Slight preference for HBS btw if that makes any difference for advice. Thanks so much in advance!