I see from the posts in this thread that it is generally possible to check bags well before a train leaves. Is this always the case.

I will be getting off a ship in Vancouver at around 9am, but our train does not leave until after 5pm. Can we go directly from the ship to the train station, check our bags, get tickets, and then come back for the train later?

We are going to be going to Seattle, so we will need to clear us customs before departure.

Thanks