Applications for military / civilian service deferment or exemption must be submitted as early as possible. Last-minute applications are much less likely to be successful.
Information about the main legislation governing military service deferment and exemption, and the relevant forms, can be found at:
http://www.vtg.admin.ch/internet/vtg/de/home/militaerdienst.html.

Information about Contacts for a confirmation letter to justify deferment of military / civilian service: