From the look of it, you're talking about meal service aboard the Crescent. Unlike Amtrak's bi-level trains, the Crescent runs with a single-level dining car. That means the seating is more limited. For breakfast and lunch (which are first-come, first served), my suggestion is to not wait for a formal invitation. You might not hear a timely announcement that the diner has opened. The PA system often doesn't work in every car. And crew people sometimes "forget" to tell you in person. Simply head for the dining car on your own (if you've just boarded, wait until after the conductor collects your ticket). If the staff tells you that meal service won't begin for another twenty minutes or so, go back to your seat. But don't wait too long to return to the diner, or you could find yourself added to the end of a long waiting list.
Dinner is a different matter. Obviously, choose the first seating if officially asked. However, when single-level trains are crowded, some conductors decide to serve meals "one sleeper at a time." In other words, the passengers in sleeper "A" will be called to dinner first. When they've finished eating, those in sleeper "B" will be called, followed (eventually) by "C." Unfortunately, anyone traveling in the final car is half-starved by the time they sit down to a very late meal. And they invariably discover that several menu items are sold out.
So if you're really hungry? Don't wait politely to be asked. Be bold. Head for the diner a.s.a.p. and stake your claim on the first empty seats. On crowded trains in particular, it's definitely "survival of the quickest."
[This message has been edited by dilly (edited 12-26-2004).]