Let's say you serve a 35-year military or RCMP career and get your maximum annuity. At age 60 your CPP kicks in if you wish to take it early, but you get two-thirds of it. You get them both. There is no OAS or GIS at that time. At age 65, benefit reduction kicks in. The amount you would have received at 65 gets deducted from your annuity, and if you are eligible for OAS it applies at that time.
On November 3rd, 2009. See this statement in context.