when do buds grow the most?

in what general weeks of flowering do you see the most bud growth?

Not a pro but I know that the first couple of weeks the plants take time to start changing to the flowering stage and there is very minimal growth. As for faster growth plants go through a growth spurt sort of. I think it is probably different strain to strain but I know the Alaskan thunder fuck I got really swells up about 10 days before harvest. The buds almost start to disappoint you then you comeback the next day and daaammnnnn.

most of the weight is added in the last couple of weeks

Like a bunch of people said it depends on the strain and pheno. Basically, what tends to happen is when the hairs get tired of waiting on pollen the buds swell up and the hairs wilt(turn orange). It's almost like a false pregnancy.