In Pardon My Past Phoebe went back to 1924 where Leo and Piper were past lovers. But in The Demon Who Came in From The Cold Piper is altering his birth certificate he was born in 1924.
Cole tells Phoebe and Leo of the target time and location but doesn't find out these details until the next scene during the meeting.
When Cole is talking to Vornac, Vornac says they've been brothers for 100 years. Earlier in the season, when Phoebe is at the historical society looking up Cole's background, the women mentions that if Cole were still alive he'd be 115 years old, meaning Cole would've had to join the brotherhood at 15. It is possible, but not likely that the source would have chosen someone so young to be in the inner circle.