FYI, you have reinvented the French Republican Calendar[1], only you missed out on decimal time (1 day is 10 hours, 1 hour is 100 minutes, 1 minute is 100 seconds; 1 second is 0.864 conventional seconds)
60 is probably best, tho.
edit: And I just realized I had a typo up there; I wrote "13 months" when I meant "12 months". D'oh.