Reasonable goal?

You're at a very good starting point.

Your breakdown (630 (Q39 V35)) is a solid start w/o prep. You will need ~8 points in math and ~3 points in verbal to get into the 80 percentile in each section, getting you a 700+ score.

I started off with a 550, 1st GMAT attempt was a 610 and 2nd attempt was a 710. Since you're already signed up for a class the best advice I can offer is give the class its due time. MGMAT requires ~10 hours every week outside of the class to finish all the reading and practice problems. Make sure you use the MGMAT tracker as your error log as this will help you get through roadblocks to achieve your goal. Also, I'd recommend finishing the 6 practice tests according to schedule to get the canned review by a MGMAT employee as this will help you maximize the benefit from the class.

Best of luck