I studied on and off, totaling maybe 20 hours between December and mid-July. My original diagnostic test was 630. A week and half before the GMAT I went into high gear and devoted a week and two days to prep that took the test.

Kaplan GMAT - Read and did all problems
12th Edition - All problems
Kaplan 800 - Did most of the problems

Took 3 practice tests online, and they said 630-700.

SURPRISE on test day!