Mine turns 2 on Friday. it is just over 10" and 8 pounds. There is another member on here with a 2 year old that is almost 30 pounds. They all grow at different rates but if raised right I believe they grow quickly.
Look at @Maro2Bear
Yes....don't over engineer any enclosure for your young sully. Make sure you have your heat, humidity, lighting taken care of, coupled with plenty of food. Don't skimp on the food! They eat, sleep and grow. Given proper 24/7 conditions as posted by @Tom and others on the Sully care sheets, your sully will thrive!