what time do you need to be at the station

1/2 early

Correct

Make sure you bring seat cushions. The chairs aren't very comfortable.

Half hr before the train leaves

I got there about thirty minutes before we left

15 minutes is good!

Early is on time and on time is late....

I arrived one hour before the train departed to check in, avoid the late passengers and look around the shop for souvenirs..

We were there 45 minutes before the train left.