Kylie Jenner's maternal instinct might start to kick in early -- it's the first time we've seen her hold Dream Kardashian -- and she's doin' it like a pro.

Kylie posted the vid Saturday with her newest niece, and while it's unclear whether Rob or Chyna (or both) gave her the green-light  ... both Kylie and baby seem pretty content. 

Look out Tyga.