My, my he is such a little doll!
As far as his weight is concerned, I think there is just no true way to tell besides time. Bella weighed 3lbs 2 oz at like 16 or 17 weeks I think. By the charts it said she would probably weigh around 5lbs full grown. Well, she nearing 6 mos and a week ago at the vet she weighed 5lbs 2 oz. I'm guessing she will be closer to 7 lbs or so full grown.
Now his coat may or may not start breaking around this time. Bellas did! It is still going through that change and probably will for a while to come! She is going through what I like to call an awkward stage.

Somebody with more experience may come along and correct me because I'm not 100% sure of any of this, but I believe you actually want their coat to "break" a little bit later on. Can't remember the reason exactly, but if I'm not mistaken I think it has something to do witheither texture or color, or both. Although, you and I aren't planning on showing our Yorkies none of that really matters!