I've done cold bluing - practically instant and very similar results.

I had some chaps on the ranger forums do a walk through of the patina process, here's the link if anyone is curious:

http://www.knifeforums.com/forums/showtopic.php?tid/816355/

hope that helps. I had just worked up the courage to patina my ranger, but then the Marine Tuf Cloth finally arrived from TAD gear, so I didn't have to. I may still though, if I get bored enough

I took the plunge! I put the ranger into the patina bath

I'll let you know what happens, and add pics

lol...
chaps.
the afgan LOW left in cinegar (I think) came out awesome and really really dark.