actually every week or two is all you need to change the water when you are cooking. if you changed it every day or two it would be a collossal waste of water and energy. You just want to get rid of the phosphates that have been turgored out of the rock before they have a chance to suck it back up.
the cooking process doesnt even really start until aboout the 3rd or 4th week IME, so two months is kind of minimum top really see any benefit out of it
you can read the basic program here....
http://thereeftank.com/forums/showthread.php?t=66551
If you have the time and energy, cooking your rock before tank start up is about as beneficial thing as you could ever do for yourself and you will have a serious head start and advantage over if you didnt