I can't answer to the chinchilla sand, except to go along with the advice already given - avoiding any super fine stuff that babies may ingest. However, I definitely go along with the "add dirt from the yard" advice! Having fought coccidiosis once, I don't recommend it ... it's definitely NOT fun! I now dig a small clump of sod (a three or four inch clod) from my back yard, water it in a small cup or tray for a few days to set it, and put it in the brooder with my peeps. They love to pick and scratch at it, so it's s great boredom buster, but they're getting exposed to the back yard microorganisms at the same time, while they're still on the medicated chick feed. In my book, that's a double bonus!
Hello! Welcome! Ive used sand (beach sand) in my chickens coop (or brooder) as bedding, from day 3 (when i got them from the hatchery). I live on an island where all the "dirt" is sand so its readily available. My chickens did not, however, start taking dust (or sand) baths until a few months old. They like taking baths in the sand now and take them every day. Im not familiar with chinchilla dust sand, but i know that regular grain (beach grain) sand for my chickens has been perfectly fine for them, even at a young age. I would recommend it for coop bedding, too, in mild to warmer climates 
All i do is take a sifter and i sift out the chicken poo and other particles, like feathers, etc once a week and it is easy, keeps the coop very clean! Good luck!
