most high quality springs won't settle much at all after the first couple days, so get it aligned as soon as possible to save your tires. as for 2 or 4 wheel, most places will take the measurements for free to see if the wheels need to be aligned, because if they do, then they make money. So they will tell you if you need a 2 or 4 wheels alignment, depending on if the rear wheels are out of spec.