Welcome to Yorkie Talk ranger5598.
Whoa! Stitch would make my two 16 pounders look tiny! I refer to mine as Yorkzillas.
Chuy didn't join us until he was a year old, so I have no idea about his growth.
We got Jezebel as a puppy and I weighed her every week just to make sure she was eating enough, expecting a gain of 2-3 oz a week. This is how it went:
Beginning weight, per vet: 32 oz
1 week (home postal scale): 34 oz .... +2oz
2 weeks (vet): 38 oz .... +4oz
3 weeks (home postal scale): 50oz ... +12oz
Do the math, her rate of growth was over 30% increase in just one week! In the 8 weeks to follow, her weekly weight increase ranged from 6.6% up to 24.1%. I stopped doing the weekly weigh-ins when she was 38 weeks old and a bit over 10 lbs, and she eventually topped out at about 16 lbs.
I kept all of her weigh-ins on a spreadsheet and showed it to my vet, and he just looked at it, shook his head, laughed, and said it was amazing. He said that if she were a large breed dog it would definitely be a problem, but since she was a smaller breed he wasn't concerned. With the larger breeds their joint growth can't keep up with their bones and body mass and it is painful until their joint growth catches up.
I love the terrier confidence and spunk and had always wondered what it would be like to have something larger than my Yorkies, such as a Cairn, Norfolk, Westie, etc. Now I've got that all in one package!