You are in the perfect position to pass this exam. Like CPA-Valenz said, this hour requirement is probably more important than the week-span requirement. However, don't overload yourself. After a few hours, go take a walk, clean up the house, watch TV, or do whatever else you want to take a load off for a half hour. Then get back to it.
The hours and days that you spend studying aren't nearly as important as the quality of your study time. If you aren't absorbing anything, take a break and clear your mind.
Memorize the standard report WORD-FOR-WORD. I know that sounds ridiculous, but you'll be able to answer a lot of the MC questions (and probably a few of the sims) through that memorization. Since you've recently graduated and recently taken an audit course, you are still in study-mode and will rock the exam. Three weeks is definitely enough time given your situation.
Good luck!
Allen A
FAR (2/2/10) 97 - AUD (2/23/10) 95 - BEC (3/8/10) 92 - REG (4/3/10) 95 - Ethics (4/6) Passed