DD is 16 weeks old (will be 4 months next week). Up until now, we've been cosleeping. I'm pretty sure she's hitting the 4 month sleep regression because she's now waking every 2 (sometimes 1!) hours. With 2 other LOs, I just cannot sustain nights under these circumstances and know that we need to sleep train very soon, which includes transitioning her to her crib and nixing the swaddle/paci. That being said, I'm not sure her temperament will allow the CIO method. If I let her, I'm sure she could cry for hours on end (much like her older brother, who took 10 months to sleep train...ugh).
I guess I'm just looking for advice/hope. And I'd like to have a plan in place for when we buckle down and officially sleep train. Will CIO work for a baby with her temperament? If your baby was difficult to sleep train, how long did s/he cry for in those first few nights? Send me your success stories!