I am not sure if they vary by breed, but from what I hear spurs really don't start forming on roos until closer to 1 year.... any little bumps you see on baby chicks don't mean anything - they could be on girls or boys.
My rooster will be 1 this month or next. He has 3/4 inch rounded spurs now. I only noticed because he is getting really aggressive lately. I can't believe the kick that he packs! He'll need a new home once this hatch happens.