My normal boarding station is Tacoma. As long as you're fully e-ticketed (or, in unusual cases, paper) there's no need to be there super early if you don't need any station services. I do like actually waiting on the platform rather than in the waiting room, which seems to always have a middle school tour group waiting for the same train, so I get there early enough to find out exactly where my car will be (can never guarantee which end of the train). Mostly I get there early because traffic can be unpredictable -- like my last trip, when I got near the station and discovered the bridge over the river was closed and I had to take a 5-mile detour to get there!