Well you are off to an excellent start. With a summa cum laude from a top 10 + a nice beginning in a consulting firm, you are actually all set on the way towards building yourself the strongest possible application as you work towards business-school. for the GMAT - the answer is simple - take it until you get the highest score you can. If you are aiming for Top 10 schools, a 700+ is great, a 720 or higher, even better. And since you have the unchangeable things (alma mater, undergrad GPA, first job) all set up perfectly, you just keep retaking the GMAT if you need to till you get your score.
The other thing is, since you are planning already - think about one if not two community service/volunteer positions that you would be interested in taking and keeping and eventually taking a leadership position in in the next years.
And good luck!