Pullet. I've heard that the SS is a tricky breed, just like the Wyandottes. I had one that I was sure was a roo pretty much until she laid an egg. Her wattles had come in and her rose comb was red at about 3 weeks. From the lack of development going on once the wattles appeared, I'd say pullet.
don't toss that cutie out until she crows or drops an egg
