"Yearling" covers a pretty broad time range. My first bp, who is now about a year old, is about 230g, which I contribute to the fact I had him on fuzzy mice for the first few months I had him. On the other hand, a pair of females I bought as yearlings in October were about 500g when I first weighed them. Not totally sure their exact age, and I suspect I might have been overfeeding them because they're up to 750 now. It seems to really depend on how much you feed them.