The 'crazyness' period is probably 1-5 minutes. After that, you can still feel "high" for another 20-30 minutes I'd say.
Note: The crazy feeling is only out of a bong (which you're supposed to use). I tried smoking it out of a pipe and got some effects. You also have to hold in the smoke for 20-25 seconds MINIMUM as Salvia does not take effect immediately like tobacco or marijuana smoke.