I've got to say I hate the term "co-sleep". It sounds like the worst combination of politically correct and new age jargon
Anyway, we started Rebecca out on a mattress on the floor in our room. We would both lay with her until she fell asleep then move to our bed. When that seemed to be working fine we moved her to her room and again lay with her until she fell asleep, usually singing her to sleep(me in the other bed in the room and my wife in the bed with her) and then left. We continue to do this to this day (almost 1 year later). Many people tell us we are crazy but since everyone enjoys this time why not?
Most nights she slept through but sometimes she would wake once during the night and need some reassurance.
Recently she has been waking up around 3AM and simply getting out of her bed and climbing between us in our bed. Sometimes one of us wakes up but sometimes we do not know she is there until the morning. On weekends we do not mind this at all but during the week if we are awakened by her we will wait until she falls asleep and move her again because otherwise the activity of us getting ready for work means she gets up very early in the morning.
For naps we usually rock her to sleep then put her in her bed and leave the room. She is fine and pretty much from the beginning just got out of bed and went to find us when she gets up.
But, she has to this day never fallen asleep on her own with no one in the room. Since she has attached well and is interesed in being a "big girl" we are debating trying to get her to go to sleep on her own after we pass our first anniversary date and trying to come up with a strategy.
Basically I would recommend doing whatever you can to foster attachement and then just enjoying your time together.