One think I keep in mind is that the wake turbulance tends to descent with 1000' /minute ,so ,if you make good use of the TCAS,you should be able to predict,or avoid most enroute wake turb.You should also consider wind,type of the aircraft ahead..
Lateral displacement,maybe considering actual xwind,you can calculate how much is the displacement.
Anyway,more than 3 minutes behind another plane won't give you any significant turbulance.
So,if you have a 60 kts xwind,in 2 minutes the mass of air will move 2 NM,I think.And descent 2000' (the wake turbulance,I mean).