18 gauge wire on 18 branches
To answer your question, yes, connect the hot leads to the hot #12 and the white leads to the white #12 neutral, wiring all the led lights in parallel. You can group or pigtail them.
You need to check the load in the bedroom to make sure you don't overload the circuit but led lights have such low wattage my guess is you'll be ok.

Where did you buy the chandelier, online? Is it approved for use in the area you live in?