It may be helpfull to cool down your horse after a ride! If you feel your horse needs it find what works for you!
I like lunging before I ride. It helps get any "spring fever" or "freshnesss" out of my mare.
I always lunge before a ride just to get the "freshness" out of my horse. It could serve as a warm down but it would need to be short after a ride. Before can be longer.
I think b4 you ride but it really depends on your horse, but doing it before can help if they need to be calmed down
I narmally do it before I ride just to get them listeneing and warm them up, especially if they are a little crazy at the moment
I do it sometimes after a quiet ride or if I do a lot of jumping just to make sure my horse isn't moving stuff or anything like that. But I don't do it for too long, only a few minutes.