That being said you COULD overload a few semesters to make up the extra subjects, but I wouldn't recommend that you count on doing that. For your first semester, I'd say do the normal load, and your second semester, you can use as a test to see if you can overload. Be careful you make your mind up before 31st August though.
My degrees require 4.5 years of study. I'm able to fit them in four years because I've overloaded once, two subjects are outside normal sessions, and since there's one subject left, I'll just overload once more.