What to do with Elder

[OllieMartin]

Once you've made some Elderflower cordial, you can try my summer favourite drink, the Elderflower and Lemon Tom Collins:

1 oz Gin
1 oz Limoncello
1 oz Elderflower
1/2 oz Lemon Juice
Top up with Lemonade (or 2tbsp Gomme & Top up with Soda Water)

[LostGoddess]

So far I have made 7 litres of Elderflower cordial using HFW's recipe and some Green Gooseberry & Elderflower jam. But what I'm really excited about is my elderflower champagne which I started last Wednesday. But I got mixed up with the recipe and left it for 4 days before checking for fermentation instead of just 2. Well I checked it today and no sign of fermentation, so I have added a pinch of yeast as HFW instructs. My question is whether I left the brew too long before checking it? I put alot more flowers in than the recipe suggested, and some of the ones on the top of the brew had signs of mould on them. I removed these and added the yeast. Do you think it will be ok? It doesn't smell 'bad', just as a bit vinegary... that'll be the white wine vinegar in it!
Any comments appreciated as this is my first wine making venture.