GMAT Strategy

I just took my first GMAT and got a horrific score of 420 (30 percentile in verbal and a measly 14 percentile in quant) . I only casually studied for 3 weeks, got a 520 on the practice and stopped studying for 2 weeks ( NOT smart on my part, I know.) So now, I am extremely motivated to study hardcore for 3 months to achieve the score I need (over a 550). My study plans are as follows: Since my obvious weakness lies in quant, I plan to study 6 nights a week for 3 hours (2 hours devoted to quant and 1 hour to verbal). My study materials include: Manhattan GMAT quant Section (Month 1), Kaplan 2013 edition (Month 2), and the OG 13th edition for the last month. I will take a practice test every 2 weeks to monitor where I'm at and to pinpoint my weaknesses. Do you all think this will help beef up my official score to a 550? (I know a 550 isn't too high in the grand scheme of things, but the school I want requires that score and I am a VERY nervous test taker)! Any tips, advice, or suggestions would be greatly appreciated!