Elderflower wine is among my favorites (and is my wife's favorite) and I make small batches several times a year using dried florets. I never add grape juice and use about 1 oz of dried flowers per gallon (I have 3 gallons that I just racked before I left for work this morning). I aim for a starting gravity of about 1.090 (about 12% ABV) and use 71B. So much for the backstory.
Elderflower wine is an old folk wine in Britain and many people who make it bottle the wine just as the yeast cease fermenting and are ready to drink it (over-carbonated) a few short weeks after bottling (typically in plastic soda bottles to prevent bottle bombs - a real hazard in folk wine making). Bottom line you can certainly allow elderflower wine to age and like any wine it improves as it gets older but you can drink this once it has fully cleared, at most, 3 or 4 months after pitching the yeast. You can prime this so that it is sparkling - but dry, or stabilize and back sweeten or simply bottle the wine bone dry (it may need some additional acid to give it a little more zing).