Depends,What kind of steel,On my SS blades I start with a cold kiln,Wrapped blades are put in and the program is started,it goes through 4 heating steps to get to austinizeing temp.
On carbon steel blade I bring my kiln up to temp and let it stabilize for about 30 min,then put the blade in and soak to 5-10 min.
Works for me,YMMV.
Stan