How early to arrive at train station before night train departure?

If you have your tickets in hand, 30 minutes before departure is plenty - in theory even 10 minutes is OK, but maybe don't push it as a first-timer!. There are usually no check-in formalities, you find your track by means of the train station board (sometimes they are TV screens) just like you find your gate at an airport and proceed to the right track. Once on the platform, you will have to locate the right car. The car number is displayed at the door of each car - usually in the door window or on a plate next to the door. The berth numbers are displayed at the door of each compartment. If you are afraid of getting confused, read your tickets before arriving to the station and locate the car and berth number on the tickets so you know which train and car numbers you are looking for. Track is "Voie" in French, car is "Voiture". Tracks are sometimes designated by numbers, sometimes by a letter.

Rosemary,
Just recently returned from Europe and we rode 2 night trains. We arrived about 30 minutes ahead just to make sure we were ready and weren't runningto the train in case we were delayed somewhere else. That being said, neither of the two trains we were taking were at the track until about 10 minutes before our departure anyway.

We did take one out of Paris Gare de l'Est and they didn't announce the track until shortly upon it pulling up to the end of the track.

Michael: About how many hours of sleep did you get on each night train?And did the experience meet your expectations, was it what you expected, or different--regarding privacy, comfort?This input helps us in giving advice to others.

We went from Rome to Paris on the night train.
I think an hour before hand is plenty. Assuming you have your tickets and cabin assignments beforehand, just read the train tables and find your platform. The check-in is on the train. We ended up waiting around on the platform entrance as the train didn't pull into the station until ten minutes before departure.
Read your ticket for your car number and class and walk down the platform looking for your car number. I had to lift all my kid's luggage onto our train car and wheel it to our cabins, but there was plenty of time to do that. I didn't feel rushed even with ten minutes to departure. The steward then showed up to confirm that my family and I were on the correct car and the correct cabins.
I have traveled both first and second class in the past and I will say this time around, first class was worth the extra money. We had two first class cabins with an adjoining door.
As for sleep- I got more sleep in first class than I did when I rode in second class. Better accomodations I guess.
Note, this was for the night train. There was a different check-in procedure with the Chunnel Train between Paris and London.

Thank you all for your replies. It's very helpful to know what to expect! Regarding luggage, does your luggage stay in your compartment with you (we are taking up one whole 4 person couchette) or is there an opportunity to check luggage?

No checked luggage....you keep it with you.

Something to think about:

If you take a night train from, say, Munich to Venice, the train originates in Munich. If you go to the platform 30 minutes before train time, it might be there. However, if you were to catch it in, say, Innsbruck, it probably won't get to the station until a few minutes before the departure time. So, if you get there 30 minutes early you will just be wasting you time. You should get there a few minutes before arrival just to find the "train makeup" board. Find your coach on the board and observe the letters (A, B, C, D, or E) above the coach on the board. Then find the corresponding position below the letters hanging above the track. That way you can get directly on the car with your accommodations, instead of just getting on and having to walk through the whole train with your luggage.