7 wks is usually plenty of veg time for indoors with the height restrictions you've got. With SOG that's more than you'd want as well. Height is more of a crteria to use than age anyway. And as has been said, depending on the strain, they should double in height or more during flowering. If they're rooted cuttings or plants beyond the seedling stage (3 wks or so) with another 4 wks of veg will usually yield 2-4 oz. dry. This should give you an idea of what to expect.