Can a 9 week old chick start growing saddle feathers?

I have had bantam cockerels that show male feathering characteristics that young.

 

Yes, it's possible.My brabanter cockerel began showing apparent saddle feathers at 8 weeks.

 

Absolutely! I had a Golden Cuckoo Marans last summer that displayed, not only saddle and tail feathers, but he crowed around six weeks and was mounting his brooder mate at nine weeks.

You don't mention what breed this chick is. If it's one where the roosters have multicolored plumage, you can get a sneak preview by parting the feathers on its back and looking at the pin feathers close to the skin that are emerging. If they are of a contrasting color to the outer saddle feathers, you have yourself a cockerel.