I'm not that familiar with their politics vs the ex-Yugoslavian territories, but I expect it's not all nice and dandy.
And I also know that all it can take is new elections and new leadership for a change in the "official line", at least as declarations, and it may just be enough for EU.
You would be surprised to know what is going on here, but we will not go off-topic - I will just say that the EU wants to get Serbia on its side, before Russia does. Unfortunately this cannot and will not happen - one man rules that country and controls absolutely everything - and
here I have written something that best depicts him and his character.
However, back to the topic, the date doesn't even matter that much, as long as that's - more or less - the direction (EU and probably EUR). And that makes Bitcoin quite unlikely in the equation.
Of course, the chance of an EU member setting Bitcoin to the level that El Salvador did is, in my opinion, less than 1% at the moment - and for a country like Serbia to do so is even lower. Such fake democracies that are actually dictatorships have never been and will never be a place where Bitcoin can prosper.