Toddler bed?

Am

We’re not ready to make the switch just yet but baby number 2 is on the way here in July and #1 will be 3 in October. So my question is - for his first big boy bed, do we bother with a toddler bed? or do we go straight to a twin? He’s still in his crib which I think they make a transition railing for it, but I didn’t buy it because I figured it would be in crib form for most of its life - I don’t know if I can still get the conversion kit for it so a new bed is probably on the books. Just wondering if one or the other makes the transition easier.