Assuming you are using a simple steel,and you are probably doing some sort of torch style HT,I would leave 1/16 inch.You need plenty to sand off after the HT to get through the decarb'ed "rind" and expose the good hardened steel under the surface.You will also have less problem with edge warping. When posting a question on a specific blade, give steel type,thickness,blade size,and method of HT(and any pertinent info). That way the answer can be more specific.
Stacy