You may find Liam Davey's notes on WF Croissant to be helpful. He tested it at 2%.
SnV
Buttery & yeast forward, very slight croissant taste behind the yeast.
7 Day Steep
The yeast has now decreased a little with the croissant picking up, this is still unbalanced with the yeast and butter being the forward flavours.
14 Day Steep
The yeast taste has now reduced to become an accent, the croissant pastry has now picked up in taste, this now tastes like a very buttery croissant with a touch of yeast. This has a buttery mouthfeel but is lacking the flakiness of a croissant.
21 Day Steep
No change
28 Day Steep
No change
Suggested Usage
I’d use this as an accent 0.25%-0.75%, Background 0.75%-1.25%, Main 1.25%-2%. Use with Fruit, Cream, Bakery, Custard, Spices, Nuts, Chocolate, caramel, Toffee, Butterscotch, Vanilla