Vacation accrual rules differ from company to company. In theory, you are given vacation progressively as you work through the year. That isn't necessarily a linear relationship; IBM used to heavily front load it with some odd effects on how much vacation you got during your first calendar year.
Normally, they hide this detail by letting you take vacation that you would earn this calendar year even if you haven't yet earned it. That is, if you get 2 weeks per year, they will let you take a week in February even though theoretically you won't earn all of those days until July. So there is some interesting bookkeeping being done to permit that.
However, also normally, if you are on salary they handle vacation by simply paying you your normal wage on the normal schedule, rather than having a separate arrangement for vacation pay.
If you are being paid hourly but still getting vacation, I honestly don't know what the norm is, or even if there is one. That is a fairly uncommon combination, at least in the United States.
But note that I did say "normally." It is possible that your company has a different set of policies on this. I would have hoped that they would make those policies very clear to you when hiring, and that they would be available in clearly written form upon request. So if they didn't give you a copy, ask for one; that should answer your question about whether this is how your company ordinarily handles things or not. It shouldn't be necessary to push very hard to get a copy; the company generally wants everyone to understand how this works.
It's perfectly reasonable to be surprised. But don't get annoyed, or worried, until you have seen whether they are, in fact, following their own rules. If they are, then just chalk it up as something to be aware of in the future; it's unexpected, and inconvenient for the employee planning a vacation, but if you get all the money in something resembling a reasonable amount of time that's all that really matters.
If they are doing something that disagrees with their own rules, and they don't have a good explanation for it, this may hint that they are having cash flow problems. If so, you might want to make sure your resume is ready in case they decide to close up shop.