Personally, in my own game, I realized it as soon as I had my second dragon, then my third.
You have to realize that as long as you do not have a small gold unicorne tree and a small gold cloud tree,, you only must to make one dragon at a time.
The best is to have as many trees as possible to be able to make 3 dragons regularly, and to be able to give fruits also in the ancestor grove..
but it takes a lot of time and patience to save water lilies...