7weeks should be a 200gram plant or larger, if less than that you waited too long relative to pot size and other factors. I'd expect a plant to fill a 2.5'x2.5' space with a 7 week vege. Some might get to 3x3. Maybe a bit less on both accounts, if in a soil context. Genetics have their say too, so it's hard to predict any single plant.
They will at least double in size if not restricted by the pot. Some will triple.
So, when your LxW dimensions of plant are about 70% of total coverage area, then flip. (.7x.7=.49 or 1/2, roughly)