My girls are 19 months apart. We kept DD2 in the rock and play in our room until she was almost 6 months old, so that we could hold off on moving DD1 out of the crib.
When DD1 was 23 months, we set up her toddler bed in her new room and planned to spend a few weeks talking it up and adjusting to the idea before moving her. Instead, the day after it was set up she asked to nap in it. She did great, and that was that, she's been in it every since. A little over a month later we moved DD2 into the crib.
Our crib does convert to a toddler and later full size bed, but we chose to keep it as a crib. Our toddler bed was handed down to us. If it hadn't been, we would probably have gone straight to a twin bed for DD1.