You should be able to get a routing on online timetables. Trains run on the so called Glacier Express (** see my 'FAQ' below) route 365 days a year. You will have to change trains a few times, but the overall journey time is hardly any different as in practical terms the Glacier Express trains can not run much faster than the normal trains on the line.
Please see the PDF timetable (page 244 onwards) here:
www.fahrplanfelder.ch/ fileadmin/fap_pdf_fiel ds/2019/142.pdf
** Glacier Express:
Take care with the hyped-up marketing of the Glacier Express. It is not always the best way to 'see Switzerland'
As I have stated in response to previous forum threads it is not logical or practical to travel on the Glacier Express from a base further north (such as Interlaken or Luzern) 'just to be on the Glacier Express'.
The Glacier Express runs roughly on an East - West axis in the southern part of Switzerland, so trying to access it from further north is falling into the trap of being lured by the hyperbolic marketing of the Glacier Express. In practice the Glacier Express is just an ‘exclusive’ train on a normal railway route with plenty of other normal - non supplement , reservation-free trains on it.
To understand the above, it is worth taking a moment to understand the Glacier Express and its history:
It was created (as one train each way daily) with the notion that well-healed travellers taking long holidays in Switzerland in the ‘Belle Epoque’ era (1930s) would stay in Zermatt and then also go and stay in the other fashionable resort of the time, St Moritz. The train was named (mainly) after the Rhone Glacier which has now melted so much that you don’t see it from the train and in any case the train runs under the Rhone Glacier in a base tunnel which replaced the Furka mountain section in 1982.
Points to bear in mind about the Glacier Express:
Although the whole journey is in the mountains, a lot of it is in valleys - where you get some good views of bubbling rivers but not all the time - there are some mundane sections.
In truth there are only 4 really spectacular sections - in order West to East: the loops around Grengiols and Fiesch; Andermatt - Oberalppass - Disentis; Ruinaulta (Rheinschucht aka Rhein gorge); Albula north ramp loops and spirals Tiefencastel - Filisur - Preda
The trip is a long one - tourists can frequently be seen sleeping rather than watching the view and missing the spectacular bits anyway!
the same railway lines can be travelled using ordinary local trains which are no slower in practice due to the single track infrastructure