sugar rose petals- when to place them?

[blackcatsdancing]

Hi,
i'm decorating a ganache covered cake with sugared rose petals. My question is do they get placed before or after the ganache has set? currently its just got a the crumb layer on. Later today i'm doing another layer of ganache glaze where its poured over whilst still slightly warm. I don't want the glaze to wrinkle but i do want the petals to stick!

ok. i placed them onto the still very wet but thickening ganache and they didnt cause it to wrinkle.