Start at 25 and get it dialed in at that distance. Then move back to 100, and dial it in at that range. Once sighted in, I like to shoot it a couple shots at various distances (close and far) to see exactly where she hits.
Where you want to set your gun is really based on the conditions you hunt. If 90% of your shots are 100yds or less, set it dead on at 100 or maybe 1" high at most. If most of your shots are further, you could set it 2" high at 100, etc. There is no blanket answer to your question...its based on how you hunt.