Trains run every hour on the MOB railway, see the timetable PDF here:
http://www.fahrplanfelder.ch/ fileadmin/fap_pdf_fiel ds/2019/120.pdf
The timetable PDF shows at a glance the connections from Genève, for example 08.30 from Genève gets you on to the 09.44 from Montreux.
Take any train – no need to reserve
Some personal comments about the line:
A few facts about the Montreux – Zweisimmen railway – ie the MOB (Montreux-Oberland Bernois):
The Golden Pass is historically only Montreux – Zweisimmen, only more recent marketing branding takes the ‘Goldenpass route’ east of Zweisimmen to Interlaken and beyond to Luzern.
The Golden Pass is the touristic branding for the Montreux – Oberland Bernois (MOB) railway which runs from Montreux to Zweisimmen, but after a few years of favouring ‘Goldenpass services’, the company decided it was losing its tradition and has reverted to putting the Chemin de Fer Montreux – Oberland Bernois name on publicity and train coaches.
MOB pioneered the Panoramic coach concept on Swiss trains, starting in 1976.
There are now several versions of panoramic coaches in service, but MOB keeps changing its mind how to dub each service.
It hardly matters anyway as most modern Swiss trains have large windows, even if not officially panoramic. The key element of a ‘panoramic’ coach is ‘toplight’ windows above your head but in practice very few of the major views from panoramic trains are directly above your head, so the view through the normal side part of windows is normally fine.
If you do do the MOB railway you can catch any train, there is no need to book.
1960 man / Swiss railway consultant