Some men do make initial gains with lower weights. They are usually the guys with no previous PE experience. You will of course, eventually have to increase weight over time as your penis adapts. You cannot keep adding more time with the same weight. There's no way around it.
Definitely gains can be made this way in hanging, 7 pounds is about the same intensity you would get from the [words=https://shop.mattersofsize.com/products/sizegenetics-penis-extender]SizeGenetics[/words]. If starting at 7 pounds I would definitely, as you are ready, add more weight. Getting to 15-20 pounds is a very formidable hangingweight. So, yes you will gain with 7 pounds but it will take longer than if you had a progressive routine instead.