My husband and I didn't make the decision to co-sleep with our first daughter. We fell into the concept while in survival mode as new parents. Emma Jane had severe sensitivities to dairy, egg, and soy protein through my breastmilk. The first month of her life we spent our nights walking the living room, watching Glee to pass the hours, and catching spit up with many, many burp cloths. Once we figured out the tummy-troubles, it took a while for her system to calm down. So basically, sleep was not something we were seeing a lot of - due to her cluster feeding all night long as her way of soothing her stomach. I found that by keeping her in the crook of my arm, I got a lot more sleep. I didn't have to get up and get her for feedings, and I didn't have to stay up long enough to put her back in her bed. Genius! Soon I realized we had become a co-sleeping family. And we loved it.
We decided to keep up this style of sleep parenting until it no longer worked for someone in the bed. I always made a point to put Emma down in her crib, but once she woke up for her first feeding it was into bed she came. Once she grew out of her bassinet that was against my side of the bed, I bought a toddler bed rail and attached it to my side of the bed to keep her in.
We put her crib next to our bed so that we could start putting her in there more regularly, and if I happened to be awake after she finished feeding I would put her back in the crib. We didn't start doing this until she was close to a year old.
Once this was more of a normal thing for Emma, we turned her crib into its toddler bed version because she was old enough to climb in and out. Around 13 or 14 months old we did this, and kept it close to me with the toddler rail up on the outer side of it. We also started to put her asleep with a "buddy" so that she could have something to make her feel like she was not alone. These were all steps we took to inch her out of our room in the future.
When Emma was 15 months old we decided to teach her to go to bed without falling asleep on us first. Due to the tummy issues when she was an infant we fell into a pattern of singing and rocking her to sleep. At 15 months old this was a bit difficult because she was so long and was starting to weigh more than arms could hold for 20 minutes. Yes, it took about 20 minutes to get to to sleep each night and each nap, which is another reason we wanted to start teaching her to do it herself.
The first week of this was a work in progress. We had moved her toddler bed against the wall by our bed so that she couldn't roll over to me during the night. If she needed to get up and come to my side of the bed that was okay, but we didn't want her automatically defaulting to her comfort zone.
When she was 17 months old we were 2-months pregnant with our second child. We decided Emma needed to learn how to sleep in her own room so that we could effectively co-sleep with the baby and not worry about her getting squished. We made a big deal out of picking a toddler bed (we went with IKEA) and special bedding that made her excited to sleep there. It really worked! Each night we would talk up the big girl bed and her comfy, cozy heart blanket and heart pillow. She ate.it.up.