I can't help but notice, and have been pointing out periodically throughout 3E's existence, that the rule in question doesn't actually say you have to follow the steps in order. Many people take it that way, and at one point I think even the then-Sage was one of them, but the RAW are entirely silent on this point. I interpret that, along with the occasional passage such as Hypersmurf just quoted, to allow you to do the steps in any order that doesn't actually create a paradox, and in my game, my house rules explicitly state as much (I don't think this is actually a house rule, but that makes it unambiguous).
(What would be paradoxical? Say you want a Prestige Class that requires a BAB of +6, and you only have +5. I would not allow you to take the first level of that prestige class on the strength of the class' own base attack bonus, because that would mean using something you got as a consequence of entering the class to meet the prerequisites you had to meet before entering it. On the other hand, Feats and ability score bumps are a matter of overall level and don't care what class you just took your level in. So you could take a Feat that requires a class ability you just gained, or take a PrC that requires a Feat you just gained - but not both at the same time.)