I'm a seasoned European rail traveler, so I can guess the answer to this question, but I still value other input from other experienced travelers. I'm working on some plans to "bop around Europe collecting countries" next June and July. I know how to research train times on bahn.de and I know and love www.seat61.com. But I'll ask anyway... How far in advance should I think about locking in sleeping reservations on some of the night trains I might want to take? I'm thinking about the following, in particular (all of these are sometime in June or July but I can't be more specific than that yet) Madrid-Lisbon and return Madrid-Paris Koln-Copenhagen Copenhagen-Frankfurt
Zagreb-Munich or Zagreb-Zurich I realize I could start now, and that'd be ok. But I am also trying (in vain, I suspect) to overcome my lifelong anal compulsion to overplan everything! I'd like to just make it up as I go, but I realize that some things in Europe must be locked in ahead of time, or I could wind up spending a night on a bench in a park or a train station! or a cell?
Every country's train system is a little different, but in every case I've ever encountered; 1) there is dramatic savings to be had in purchasing the tickets as soon as they become available - savings in the range of 30-70% 2) those tickets are not available until 90-120 days ahead, so you are still much too soon for June/July. Take advantage of this time to refine your itinerary and research the wisdom of day trains vs night trains and/or trains vs low-cost airlines.
The overnight trains from Köln to Copenhagen and from Copenhagen to Frankfurt are both CityNightLine trains and are bookable online 92 days in advance with the Bahn. The overnight train from Zagreb to Munich is a EuroNight (EN) train. I don't think it can be booked online, but you can book it by calling the Bahn directly, in Germany 1805 99 66 33.
Funny - I've been wondering the same thing. I know how far in advance they CAN be booked but I would like to know how far in advance they MUST be booked - do they book up so a reservation for a 1st class sleeper for 2 is not available? We are traveling in May with a rail pass and yes I did figure out that the rail pass for us is best/cheapest/convenient.
I strongly doubt there is anyone on this forum who has access to the historical records showing at how many days beforehand a journey 'filled up' or all compartments were full or not upon departure for any journey you might refer to. Or who can forecast how many people would wish to travel. If you want an opinion for a likelihood for a particular journey on the off chance someone has made that journey and contributes here you may want to advise.
My practice is to lock in reservations as soon as I am sure of my schedule. This applies to hotels, trains, and planes.
Tom - For the overnights trains you will want to book them as far out as possible. Some of them are typically sold out a week in advance so it is hard to make it up as you go without taking a significantly amount of more time to get from point A to point B by taking several day trains.