Hi Seesagirl, first off your boy is darling. I love the silver penciled Cochins. As far as whether he is frizzled or not, there is no chance of him being a frizzle unless one of his parents is a frizzle.
As for your question about whether the feathers can curl up late, I've never known of them curling up late. In my experience, they are always quite obviously either frizzled or not by two to three weeks old. As for the other part of your question of whether a chick can have just a few frizzled feathers and still be a frizzle, all frizzled chickens do have varying amounts of frizzled feathers and variances in the quality of the frizzled feathers but the frizzling is all over their body.
Good luck with your boy!