Hi there,
A couple of thoughts here...
-It can sometimes be tough to get a 2nd MBA if that is indeed what you are aiming for; be sure you check whether it is even considered at the schools you apply to, and you'll have to really make a strong case for WHY you need the additional degree. At the most competitive schools, it can be tough to be admitted over someone who does NOT have an MBA already, fyi.
-Timing--- Round 1 would likely be tough to do a quality job with if you still feel you need a lot of GMAT prep and haven't started anything. Not impossible, but quite tough. Perhaps Round 2 would work, or the following year when you have more time to research programs and your career plans etc!! In that case I'd do GMAT first and get that under your belt.
Keep us posted and good luck!