I had a Dutch rabbit years ago and they weigh between 4 and 4.5 pounds full grown, yet from what I understand the Belgiam hare can grow larger.
My Dutch was adopted as an adult, so I do not know how much he weight at 2 months as a comparison.
You bunny's adult size will depend on the genetics he inherited from each side of his family.
Welcome to the forum and good luck with you new bunny.
You will find a lot of good information, as well as friendship, on RU.