Warning -- this post is quite lengthy! :rofl:
I've played Spain quite a bit and played around with this in various ways. Long ago on the forum there was a *very* good post about this which more or less fits my experience. I unfortunately don't have a link or citation for it-- but I can give you the gist of it from my hard copy:
The five revolting provinces are Friesen, Flanders, Holland, Zeeland, and The Hague. Of those, only the last three are actually key to the formation of the Netherlands -- that is, as soon as those 3 fall into rebel control the game gives the netherlands a chance to form.
If that chance succeeds, and the Netherlands form, the new country will also include any *other* provinces that are also in rebel hands (even Hainault, Artois, and Luxembourg, which otherwise stay catholic and don't revolt on their own).
If the chance fails, then the netherlands will get another chance at such time as one or more of the three core provinces are recaptured from the rebels and then fall to rebels *again*.
The revolt percentage goes way up (around 41%) with the Calvinism event if your state religion isn't protestant or reform, and will stay that way until the Edict of Tolerance. Like all religious events in the game, the dates for these are slightly randomized and you can check your progress by clicking your religious icon in the town hall or country screen as if you were resetting your religious tolerance sliders -- at the bottom of that screen is a listing of the next coming religious event and your percentage towards it's arrival. In my most recent game, Calvin arrived in September 1542, and the Edict of Tolerance came in March of 1589 -- rather on the quick side!
Note that even if the Dutch appear, if you annex all three core provinces (Holland, hague, Zeeland) before the edict of tolerance, then supposedly the revolts will start all over again!
The bottom line is this:
-- If you are simply looking to ease your pain, and get through the revolts with minimum expense, then build up a fair sized rebel-killing army in one of the three catholic provinces and don't use it unless the rebels start crossing the border into those catholic provinces! Let the rebels have everything and take the risk that the Dutch will inherit the 5 other provinces -- you can always win them back later. Or if you are in the mood for a bit of risk, you can try to time things so that you retake Flanders (or even Friesen) right before one of the 3 core provinces falls into rebel control. That way, if the Dutch arrive, they won't have quite so many provinces to play with.
-- If you are looking for a World Conquest style game where you want as much of the world as possible to be inhabited, then you might *want* the Dutch to arrive because they are prodigious colonizers. In that case, you might go so far as to keep retaking one of the core provinces and allowing it to fall back to the rebels until the Netherlands appears!
-- If you are just a sadist
then you might be able to provoke such a wave of killing in some of the provinces by repeated sieges and rebellions that you actually drop province population below 5000. At that point you can send a colonist and if he is successful, he'll convert the province back to Catholic, which should end the revolt there... maybe (I've never done it).
