Oh that would so much better a deal! That's sort of like getting the block plane for free, on top of getting the no. 4 for a great price =D> I have one of these smoothers and it's a real performer, I have it set up as my super smoother.
If you haven't fettled a new bench plane of this level before expect it to take more than 5-10 minutes. You can zoom through the work if you don't like to hang about and you know exactly what you're doing, but a first-timer should just do it at a comfortable pace and let it take as long as it takes.
There are a few things you must do and a few optional things in fettling (like rubbing down the woodwork). Honing the iron is the most obvious must-do, but getting the cap iron fitted to the back of it is as well and this is likely to take you longer. The fit needs to be perfect and you'll probably need to need to do a few rounds of work and checking until no light at all shows through under the leading edge.