But, I can tell you what we did. So, here you go:
First of all, Cub sleeps with his trusty Mr. Lion and we also have a sound machine going while he sleeps. Some people hate the idea of sound machines and some people also hate the idea of a sleeping toy. Like I said, you just have to do what works for your little one. So. We have a sound machine for Cub (it plays a rain-ish sound) because we live on the corner of a prominent street in our neighborhood, so there is a substantial amount of traffic noise. And, Mr. Lion, well, we just innocently tossed him in Cub's crib one day and the rest is history. That kid is IN LOVE WITH MR. LION.
So, when Cub hears his sound machine come on and when we hand him Mr. Lion, he knows it's time to sleep. These are his "cues" so to speak. I'm kind of big on not having anything attached to the crib, like mobiles or toys and such, so Cub was used to not having a playground in his bed. So, that first night, we turned on the sound machine in his new room, handed him Mr. Lion (who we now keep stashed in his closet, so he's only out during sleep times), and laid him down in his new bed.
And he looked at us like we were on crack.
It took a couple of times of going back in his room and putting him back to bed, but he eventually fell asleep. We let Cub cry it out when he was an infant, but let me tell you, hearing my little toddler cry in his big boy bed was one of the hardest things for me. He loves his new room and he loves to play on his bed, but it's still all very new. Each time we went in to put him back to bed (he crawled out about three times), we'd kiss him and soothe him before laying him down. The next day, he took his nap without a problem. And the next night, he went down like a dream. He actually did great with it for a while, until yesterday afternoon, when he fought it again with his nap. So, like before, we did our little dance of me going in there and putting him down every time he got up (again, three times). I wasn't as sweet this time--he knew he was supposed to stay in bed and he has proven to us that he can, so my expectation was higher now. I mean, I wasn't MEAN, but you get what I'm saying. It was still hard for both of us, but after about ten minutes, he went to sleep. (And then I cried. Because I'm an emotional pregnant woman.)
And then last night he laid in bed and chatted to himself for a few minutes before falling asleep. That was awesome because he never got out of bed. He can chat as long as he'd like at this point, as far as I'm concerned, as long as he's not playing in his room and as long as he is in bed.
So! That's how it went for us.
And now, for the advice part. Eh .... each child is different, so I definitely can't tell you when you should move your baby. There are several factors that play into it. We moved Cub out of necessity, of course, but also because we knew he could handle it. You just kind of know your child and your gut tells when it will be okay. And even though we've fought it twice so far, we haven't fought it the other eight times he's gone down, for naps and bedtime. And really, by "fight", I mean having to lay him down a few times. It really isn't much of a battle!
I realize that Naomi isn't coming until June, but we wanted Cub to not only be in his new room when she was born, but we also wanted his new room to be his new kind of normal by the time she arrives. We wanted him to be 100% comfortable in it, giving him plenty of time to know that that is his own space and that he wasn't kicked out of his nursery! By the time Naomi comes, Cub's nursery will be old news to him. And that was our goal.
I think the only "advice" I could really give is to stay consistent. If you are set on your child moving, then be set on it. Don't revert. Don't give in and put them back in their crib. The reality is, they can sleep in their big bed. It isn't an impossible task you are asking of them. It is new and it is an adjustment, so be kind, but be consistent. Just because they might cry does not mean you are being unkind. Chances are you don't remember being put in your "big" bed and your baby won't, either. It's just kind of something that has to be done. Babies show displeasure through crying, kind of like adults when they have to move and meet new people. We don't cry, but we kind of get a knot in our stomach and we feel uncomfortable with transition. Babies are the same way. Transitions can be hard. But, really, like I said, be kind about it. Make sure your baby is worn out by bedtime (or nap time, whenever you choose to put them down in their big bed first) so they will want sleep.
And then be resolute that you will get up and put them back to bed as often as it takes before they really understand what is expected of them.
So! That's my advice. Right now I can hear Cub babbling over the monitor, playing happily in his room, and I need to go make breakfast! But I love that he can get up and start playing in the mornings. It's so fun. The reward is worth it, trust me! Just stick to your guns, follow your gut, and go with it.
Have a lovely day!