Daily, 3 x heaped tsp (approx 5-7g ea - yeah I know about diminishing returns and the studies you could cite saying 5g daily is the max useful dose etc but I don't tell you how to live) morning/pre wo, post wo and last thing at night. My personal opinion is that creatine and L-glutamine are the two most basic supplements that should be in a BBers stack and there's factual information to back them both.
What effect have I noticed? Like virtually all OTC supps (like DAA in that other thread) I don't think acute usage of a single substance will provide a significant tangible gain, however, sustained long term usage of a variety of supplements can be of benefit as the cumulative effect of many 1%'ers adds up over time (particularly in times of sustained caloric deprivation). Is it quantifiable? No. It will vary from person to person like everything else in this game. At the end of the day if you feel there is a benefit to supplementing with it (within reason) then go for it.