My son has a convertible crib, too. We transitioned him at 18 months, though, much earlier than your daughter. It was the easiest thing in the world. He didn't even bat an eye. I'm not sure if that's just his personality, or because we made the switch so early. (He'd gotten out three times, and that was plenty for us.) To answer your question: yes, making the switch is going to affect your daughter's bedtime routine somewhat. How it disrupts the routine and for how long, however, is anyone's guess. I'd start talking with her about the change early, though. "You're such a big girl, I think it's time we take down that side and let you sleep in a BIG GIRL bed." Talk it up so it's not a surprise. If it's safe, I'd even have her help with the transition. Maybe buy a new blanket or sheets or pillow and put them on her bed the first night, so she's excited to sleep without that fourth wall. Otherwise, keep the routine the same. Business as usual! I wouldn't lock the door on her. For one thing, she needs to be able to get out of the room if she has to pee or has a nightmare or worse, if there's a fire or an emergency. If she gets up and finds that door locked, it's going to freak her out. Besides, you say she can get out of the crib now anyway, and the door is shut; does she routinely come find you after bedtime? If so, don't change how you handle it. (I'm assuming you say, "Nope, bedtime" and march her back to bed. She'll find comfort in continuation of this routine.) Hopefully, your daughter will take the switch with ease; worst case, it might take a week or so. Look at it this way: one week with disrupted sleep is WAY better than trying to lift the three-year-old in and out of their crib every morning and night! Good luck!