Hi muggergammy,
To start, a 580 is a solid initial CAT score (the Average Score on the Official GMAT hovers around 550 most years). In addition, you've given yourself plenty of time before your planned April Test Date - which is great! With a Score Goal of 730+, you will have to make significant improvements to how you handle BOTH the Quant and Verbal sections (and by extension, you will have to learn and practice some specific Verbal Tactics).
From what you describe, your immediate study plan is 'book heavy'; unfortunately, many Test Takers who study in that way end up getting 'stuck' at a particular score level. The OG books are great sources for practice questions, but they're not designed to teach you Tactics, patterns or the little 'secrets' behind the GMAT - for those, you'll need Course-oriented materials.
Before I can offer you any additional advice for your studies, it would help if you could provide a bit more information on how you've been studying and your goals:
1) How long have you studied so far? How many hours do you typically study each week?
2) When are you planning to apply to Business School and what Schools are you planning to apply to?
3) Going forward, how many hours do you think you can consistently study each week?
GMAT assassins aren't born, they're made,
Rich