Hey. I'm making a cake for my boyfriend's 21st!

I bought a genoise sponge that i have in the fridge ready to be iced with sugarpaste before decorating with coloured sugarpaste. The birthday is in 6days and I was planning on covering the cake today (after filling it with jam and buttercream).

The cake is fine for 5weeks since i got it..but i'm not sure how long the sugarpaste or filling will last/how it will store. Can anyone help?

Thanks.