The answer to your question is going to be specific to you, and will depend on how well you are shooting with little to no wind. Long range shooting is all about variable elimination/control, so the key to learning the wind is to get the rest of the fundamentals down on low wind days. When you are boringly consistent getting hits doing that, then and only then will you be confident that on a windy day it was indeed a poor wind call that caused a miss. If you are limiting your shooting, and thus your learning, because the 338 is too expensive then you are shooting the wrong round for training. Go back to a 308 or other relatively poor wind performer and learn with that - it will show your mistakes in wind calling better and allow you to better tune that skill with less expense.