Putnam practice sessions are held every Tuesday from 12:30–2:00 PM during the fall semester. In 2018, the practice sessions are being led by Dragos Ghioca; please visit that web page for current announcements and problem sets.
The 2017 Putnam examination was given on Saturday, December 2, 2017; UBC had 17 students participate (as well as graciously hosting two University of Waterloo students who were working in Vancouver this semester).
The faculty advisor for the Putnam practice sessions through 2017 was Greg Martin, who is on sabbatical in 2018/19. The math department's Putnam FAQ has more information, as does the official Putnam web site.