Your best bet would be to play around on www.voyages-sncf.com for the Annency-Chamonix trip. I'm not familiar with the Italian rail system, but I'm sure they have a similar web site.
- Au départ - put in Annency
- A destination de - put in Chamonix
- Fill in your dates (the week starts with Monday, not Sunday!)
- Select an approximate time (select a time in the morning. That way, you can start at the beginning of the schedule. The web site only allows you to see following trains, not previous ones.)
- Click "Consulter les horaires."
The schedule (les horaires) seems to be M-F.
Sample times:
07h57-10h32
10h39-13h46
15h06-17h53
16h47-18h49
It shows a change in St. Gervais.
Hope that helps a little. Happy Travels.