I mix it 2-3 hours using a Harbor Freight 1" pump. I usually let it settle over night, or until I am ready to run it. But I would have no qualms about draining it after 3-4 hours if I was in a hurry. I don't have the time or set up to recover the methanol, so the cool thing abour this process is that it does use the methanol that was in the glycerin. It also recovers the biodiesel that drains into the glycerin when you drain the normal reaction. This was posted on Biodiesel Infopop by Girl Mark:

I did actually run Karl Fischer coulometer (looks for both free and dissolved water) tests on what this technique does to water.

I got unheard-of low water content in the resulting oil (70 ppm versus the 2000 we get here from heated settling or the 500 that the European pure plantoil SVO spec supposedly calls for)- this technique gets a LOT of water out of the oil.