I brewed an Ordinary Bitter on Tuesday, OG 1.035, and used an S-04 slurry that I had in a refrigerator and fed in a starter for 24 hours before pitching. Fermentation was very active when I checked it the morning after brewing.
The yeast seemed to really chew through this wort. It dropped from 1.036 to 1.011 in only two days (tracked with a Tilt hydrometer). Four days after brewing, it's at final gravity of 1.009. It's fairly clear (decent for S-04, I think) and smells great.
Is it a bad idea to keg it and start cold crashing it today, only four days after brewing? Is there a good reason to wait? I can't recall another brew finishing this quickly, and I usually abide by the standard "two week" model before considering kegging, so this one has me second-guessing myself.