We co-slept with DS1 in our bed for 2 years. He would not sleep unless being held in my arms.

When he was 2 we got a cute bed and put it next to ours in our bedroom, we made a huge fuss about how cool it was and explained that there wasn't enough room in the big bed for all to be comfortable so he'd sleep there. I still held him, he climbed out a bit for a few days but eventually thought it was cool. Then we started explaining that we'd move it in to his room and we had to do that quickly because the newborn in our room kept waking him up. So we moved the bed and he was a little confused the first couple of nights but i just went in and lay with him until he fell back to sleep. So then he was fine with it... most nights he wakes up once and walks to our room, i just walk back with him, give him a breastfeed and come back to our bed.

SO basically we skipped the cot stage altogether, which worked for us.