Folks,
A practical tip, if you are crossing the wake, or behind in anything smallish, the minimum distance is "as far as possible".
Many moons ago now, I was taxiying a DC-3 at YSSY (then ASSY) about 150m behind a BOAC B707-436, the blast hit the rudder so hard I felt like I had one knee around my ear, the poor old girl had to go back to Hangar 81 for a serious inspection.
In the years since, I have seen several examples of light aircraft rolled up into a ball, and only caught by the perimeter fences.
Just take great care.
Tootle pip!!