When did you start CIO?

If you are against CIO please do not comment.

I know CIO methods will be difficult to do but I am trying to gain knowledge about it and prepare! My LO is 13 weeks old and I know shes too young to do it now.. but she absolutely will not go down for bed drowsy and fall asleep alone. I’m thinking I can start it around 6 months? But I’m curious on when you started with your LO and your experience with it.

*she sleeps in her pack n play in my room. If I put her down drowsy and keep my hand on her she will scream... she needs to be rocked in my arms and fully asleep before I put her down*