A lot of ovens will overshoot the set temperature when you first fire them up. There is also the radiant heat factor which can cause the blade to overshoot the temperature inside the oven due to radiant heat off of the element, if your oven does not have a baffle of some sort between the element and blade.
Mine being 110v, it takes a long time to ramp up from a pre-heat to a higher austenizing temp. I offset this by running the oven up to the higher austenizing temp first to let the insualtion soak up heat, then let it drop to the pre-heat temp. With A2, I run it up to 1775 for about a half hour, then set it to 1250, when it comes down to this temp, then I put the blade in. Equalize, then ramp up to equalize at 1450 or whatever it is, then back up to 1775 to austenize. This helps reduce temperature bounce and time beteween target temps.
I think it does not hurt with any steel to run up to 1250 or so and equalize before going up to your hardening temp, unless the specs say otherwise.