Tail-take-off
I'm at LACC Swanwick. Some may consider this [in the en-route scenario] as poor technique....you have identified higher level and airspeed/groundspeed as relevant factors. In addition there are the multiple differences in aircraft flying characteristics and "bank" demand.
Perhaps a literal interpretation is actually impossible as this would necessitate a positioning manoeuvre before the point....this is much less relevant in a low speed/lower level environment. The phrase should perhaps be interpretted as "after xxx turn L/R heading ???" or whatever the R/T "police" mini-brains say is the appropriate book wording.
Next time you get this wiffle/waffle instruction in the en-route phase....ask the controller what he/she expects.....clarity is good for both sides.....and perhaps will be a pick-up point for the training section.
NOTE: in areas of the world where space is plentiful.....no problem...but in dense UK airspace....very relevant.