Permafrost - I think you will find the answer in your ops manual - each company has different 'ideas'. BA (when I left in 2004) preached 'Top of Climb' wind. The FMC page entry is labelled 'CRZ Wind'. We 'ex Dans' liked mean cruise wind and discovered that the difference in econ climb speed between a 200 kt headwind and a 200 kt tailwind was a couple of knots, an accuracy which the 737 does not seem to be able to achieve anyway
. We of course 'conformed'.
My present company, while absorbing many BA procedures, is enlightened enough to allow choice.
Like Old S, I use mean cruise wind, and correct the leg winds on the way. The advantages are:-
I can determine whether I will be on schedule, and give ops an early heads-up if not
If I have an arrival 'slot' to make, eg at Pristina, I can look at when to depart and what speed to programme
I can check that the fuel on arrival will keep me from stress.
C/crew get an arrival time indication
As I said, however, follow your ops manual - it avoids tears. If you disagree with it, take it up with your appropriate department.