When to Move?

So now that November is almost upon us (I mean, really, where did October go?!?), I think it is high time we turn our focus to preparing a nursery and big boy room in this house.  After all, it's a bit scary/exciting, that this new boy will be here in less than two months and I'm only getting bigger by the day which means my painting/crafting/etc. abilities are becoming more and more limited.
With two rooms to deal with, though, I have had a hard time focusing on which one to conquer when.  Originally, I had planned to work on them simultaneously with the plan being that Colton would move into his big boy room when the new baby arrived or even when the new baby was ready to move into his own nursery which would be a couple of months later because he will spend the first few weeks in his co-sleeper in our room.  My logic was simply my reluctance to move Colton to his big boy room...he's still soooo small for a big boy bed (even with rails!), plus it feels like it's in Antarctica despite the fact that it is only a few more feet down the hall (in fairness, our house has a very odd layout so the room is actually on a totally separate hall than our room and his current nursery, so it does feel far away), and I just feel so bad that so much is about to change for him.

Colton on his first night in his nursery...he was about 2 months old
PS: don't worry, I only put the blanket on for picture's sake!

But last week, I got to thinking and realized there are some kinks with that plan.  For starters and primarily, adjusting to a new sibling is already going to be a MAJOR transition for our sweet toddler...it may make more sense and be easier for him to adjust to his new room before he is introduced to his little brother.  This way, we can devote our full attention and energy to his transition to his big boy room before we are totally sleep deprived and pissy ourselves.  Secondly, from a logic standpoint, it just makes more sense...the former guest room, which will be Colton's new room, is currently empty, so working on it wouldn't be an issue.  Once we complete it, he could move in, leaving his nursery empty to be worked on as well.  In my original plan, I would have worked on it while he lived there, which would probably work as well, despite the fact that he would then be living in a room filled with his baby brother's things (including his name on the wall) which really doesn't make much sense.
So, this is when sharing is caring comes in.  I value you all's insight and opinions and want to know what you think.  I should probably alert you that I am absolutely opposed to waiting until after the baby is born to work on his nursery.  Despite the fact that the Jew in me is supposed to hold off, I have had a newborn before and can wholeheartedly say that (for me, at least) working on a nursery is much easier when you are pregnant rather than when you are sleep deprived and catering to said newborn's (and rambunctious toddler, in my case) needs.
So, friends, when is the best time to move Colty to his big boy room?  Even if you don't have children, I value your opinions...after all, it's pretty much the blind leading the blind around here anyway!  Ideas? Plans? Insight?  I value it all!