Every kit is different as genetics, litter size and nutrition play a huge part in kit size. They can also have growth spurts at different times. I have just started keeping detailed records on my kits weights this year. I weigh them daily for 1-2 weeks to make sure that they are thriving. Then I weigh once a week until 8 weeks of age and then monthly until a year old.
So far this year I have had 23 kits and my average at 4 weeks of age is 146 gms with my smallest kit (handfed and one of a set of triplets) only weighed 87 gms at 4 weeks and my largest kit at 224 gms at 4 weeks (a single kit and fed by mom).