Always sending out some scouts is a good idea. No matter what time you are in, the enemies plans are always unknown to you. Lift some of that fog by sending out units. You never know, you might find out that they are making a new addition to their base, right outside your front door!
Plus, at the beginning of the game, it is always nice to know the layout of the land and forests, where the enemy is, and potential areas for base expansions.