The thing about fragrance oils is that you don't really know what you're working with since their formulas are not disclosed, however, the only way to know whether you have a top note vs middle note is to test the FO on a scent strip like a perfumer would. OTOH, with candles you don't need to be nearly as exacting as you would with fine fragrance (perfumes) as you tend not to get the more orderly release of molecules into the air from top to base notes and moreso the notes are released all at once like a flower. This is really an advantage and makes scenting candles in one respect easier than formulating perfumes. The take home is that as with anything else you just have to test it but it is best to blend your fragrance outside of a candle first then test on a scent strip (you can actually use cut up coffee filters effectively and less pricey than perfumer's strips), then move to wax.
Sorry, I thought we were in the candle forum, but the same concept applies to scenting any medium