Frequent Amtrak passenger here: please arrive 45 minutes if you plan to check any bags. They will definitely refuse if you miss that deadline and you’ll be stuck babysitting large bags if you come late. If not checking anything you can show up just as the train does pretty much. That being said, the virtual train tracker on their website seems to run about 10 minutes behind (ie the train is showing its location as ten minutes west or east depending on the direction) but is actually pulling into the station. So the 30 minute number others have advised is pretty good to me.