When I build my first military ships, I always send them to my star bases and set them either to guard or sentry. I do this because I'm not worried about my planets getting attacked so early in the game (I play with tech rate set to "very slow") as it takes more than just a small military ship to conquer them; it takes a land invasion.

Is this what most players do with their early military ships? If not, how do you generally set your defense with your first combat ships? also: what exactly is the difference between "guard" and "sentry"?

Thanks in advance