Well, you know he won't be 5 lbs.
I didn't keep a record of what Ginger weighed at what age, so can't speak from personal experience, but the general consensus is double at 12 weeks. As others have said, every dog is different, and sometimes I swear my Bernie is still growing. He's also around 13 lbs.
Your baby will change so much over the next year. Size, hair color, hair texture...all I can say, is take lots of pictures!!!
Enjoy and welcome to YT!