Everything I've ever read about O1 (which I studied for a while years ago for work and getting back into it now for play) is to quench until it is about 140F. Which is right about what the oil will be if you've preheated it to 130F. Which means you just stick it in there until the oil temperature has equalized.
I just quenched my first and I had a thermometer in the oil, preheated it to as close to 130F as I could and quenched, when I did that the temp spiked a bit and I just gently moved it back and forth until the temperature stabilized and the oil wasn't flowing off the blade (convection cooling stage coming to an end). I believe it took almost a minute, though I wasn't timing it.
(sorry for all the F degrees but its very early)
