Only 49 days til round 3 deadline, should I wait?

Round 3 deadline for UNC Kenan-Flagler is April 29th and I've just begun studying for the GMAT. My schedule is VERY hectic as I currently work full time (40-50 hours per week), have a wife and 3 kids at home, and am currently taking 2 post-baccaularate undergraduate courses online. While my intentions are to study for 10-20 hours per week over the next month and a half, I don't know if that's realistic considering my daily demands as a worker, student, husband, and father. I am planning on taking the entire summer off to recharge my batteries and prepare for fall classes. Should I wait until then to try and study and take the GMAt once or twice in order to reach my target score? I have only taken one practice test and I only scored a 500 on it and my goal is to score between 650-700 in order to have a good chance of getting into the school that I want. Please let me know what you think and thanks.