At what age did you start?

With my son I think we started a little before age 2, but with my daughter we started at about 16-17 months!! Besides having quite a strong personality, she has also seems to have picked up on everything (including bad tricks) early from her big bro.

She's only had maybe 3 time outs, all for hitting I think, and she knew EXACTLY what was happening as she's seen her brother on that same little carpet square.