au pair visa (The Hague)

I have one question and I hope someone will be able to give me an answer. I am from Serbia, so I need au pair visa to come to work to the Netherlands (I am here now as a tourist for 3 months). Age limit is 25 years old (so it ends with 26th birthday). I can't get information does that mean that I can apply for visa before my birthday and if I get it, normally come to work as an au pair for one year?! Or it means, I can only get visa for period from now to my 26th birthday?! I tried to ask in Dutch embassy in Belgrade and Serbian embassy here, but they didn't want to tell me anything. Hope someone knows anything about it. Or at least, where I can ask about it.
Thanks in advance!!!
Best regards!!!