I'm personally doing 8 weeks. You can't let these naysayers say its too much Rosenrose. The fact of the matter is plenty of IMGs study for >3-4 months ~10 hours a day. If you want something badly enough you can do it.
I'm personally trying to hit the main subjects twice and the low yield ones (anatomy, embryo, histo, neuroscience, and not really lowyield beahvioral) once. Repetition is the key to success. You may not remember what you learned in day 1. But when you come to day 31, and have to review what you read in day 1, the read will be easier and you will retain it really well.
Another viable option is to take the Kaplan IntensPrep 3 week course. Use the first 3 weeks to attend the course and just pay attention and try to learn and understand. Then you have 5 weeks to normally do what everyone else does. But you'll be way better off b/c you will have had a good overview by taking Kaplan.
Good luck brother.