It is really difficult to judge at this age.. they all grow different and at different rates. I remember my Mickii's litter brother, he was huge for a 5 month old… but then he just stopped, while he was more to the bigger side, he was not over sized... so he still may just stop growing...ggg. Typical Basenji... keep you guessing. Best way to monitor weight is by appearance, IMO.
For example, my girls are about 22lbs, based on their size, they (if you read the books) would be expected to be more like 20 to 21lbs. But they are both solid muscle from running 24/7 with each other... so while they seem if you went to pick them up they should be light weights, they fool you cause they are heavy!.... And Franie, I wish would carry more weight for the show ring.