Heart-shaped Victoria Sponge decorated with rose petals..?

[OrangeMochaFrappucino]

I'm making a cake next weekend for my friend's wedding - it's not THE cake, it's simply a cake to add to the buffet as they've asked people to provide various things to contribute to the reception. I have a heart-shaped silicon cake mould and I like the idea of making a heart-shaped Victoria Sponge, sandwiched together with rose-flavoured cream and fresh berries and then decorating it with rose petals on the top.

What I'm not sure about is how I adapt the cooking times when using a heart-shaped cake mould? I've used it before for less important cakes and just checked with a skewer until it's ready, but I wanted to be a bit more technical to avoid opening and closing the oven repeatedly.

Also, I've seen cakes decorated with rose petals before but never used them myself - I've ordered pink sugared edible rose petals, have I done the right thing? I saw non-sugared ones as well, but assumed the sugared ones would be better for a cake!

Sugared rose petals will look gorgeous as they'll be a little bit sparkly, you could use either but I tend only to put the non sugared ones in salads.
As for cooking times can you estimate how big the tin would be if it were a circle? It seems to work for funny shaped tins. The depth will also play a part. You do tend to have to hover near the oven for the last 5-10 minutes to make sure it's perfect, but I wouldn't worry too much if it goes a little over, not if you're putting lovely buttercream with it.
Good luck!