Straight to a twin. We did with DD 2 months after she turned 2.
We put a pool noodle under the fitted sheet so she wouldnt fall out/ She is almost 4 now and still has it under there.

I'd go straight to a twin. You can start with the mattress on the floor, then the mattress on the box spring, then the full set with frame if you're worried about him falling out.

We had a toddler bed and it was useless - my daughter went from climbing out of her crib and coming into my room to climbing off the toddler bed and coming into my room. She never really slept in it.

We love to lay in bed and read, those toddler beds would have been a nightmare! Switch to a twin or full.

Our son went straight to a twin at about your son's age. We got one of those things to keep him from rolling off the side. He loves his "nest."

It's awfully nice for the parents to cuddle with your toddler in a twin bed versus the crib sized one!

We went straight to full bed on the floor at 20 months b/c baby 2 was on her way. DS had no issue with the transition. It's really nice to be able to lie in bed with him and read books or snuggle when he's not feeling well/has a nightmare. Toddler beds are such a waste.

Twin

Straight to twin - at about 2.5. I could do it over again, I might have gone straight to full instead.

We went straight to a full a few months shy of 3! No issues.

We went straight to twin. Worked perfect for DS. Never fell out, made the bedtime routine wonderful with reading stories, snuggling, etc.

Did the same for DD. Had to get the guard rails for her... she fell out a lot. And climbed out. (And has other, non related sleep issues) Think she would have done better in a toddler bed for a bit.

The conversion kit for our crib was only $30, and it allowed us to turn it into a toddler bed by taking the front rails off. That was a nice transition for us from crib to toddler bed to twin. However... if you would be buying a brand new bed regardless I would

Could you get a conversion kit for your crib (assuming it's cheap), try that as a toddler bed from like 2.75-3/25, and then make a big deal about DS getting a new big boy bed that he can pick out and buy a twin at that time?

Toddler beds use the crib mattress, so I went to a twin bed for my oldest, and bought a safety rail for the bed. Some just put the mattress on the floor, but I didn't think of that at the time.

Twin bed and I wouldn't wait until right before baby is born.

Thank you PPer. I don't know why it did not occur to me before, but you're right- we would have new baby with us in a pack n' play or bassinet for a few months after birth.

New baby goes to a bassinet/pack n play/ rock n play for a few months and then 3 year old goes to a twin. Twin mattresses are much more comfortable than toddler bed mattresses. And a bonus is that you can both lay in a twin bed to read.

DS will be almost 3 by the time new baby arrives. He is currently doing very well in his crib at 2.5 and I plan to leave him in there until a couple months before the new baby comes. I would leave him even longer (if it ain't broke, don't fix it) but I think it's silly to buy a second crib when DS would move to a bigger bed at some point anyways. Should I buy DS a toddler bed or move him straight to a twin bed? Seems like a toddler bed would be less of a 'step' for DS but is this a waste of $ since a couple of years later he'd be in a twin? What did you do? Thanks!