My LO is only 7 weeks old so we're not at the CIO stage yet, but since he's eating well and fairly content my new obsession is sleep and sleep training so I'm prepared when that time comes.

What age was your LO when you used CIO?
What made you pick that age?
Do you wish you had done it sooner or later?
What method did you use?
Do you wish you had done anything differently?
Any other thoughts/advice?