Timing

I'm not by any means a professional here, but I do love to do cakes! I've promised a baby shower cake and cupcakes for a dear family friend. I work full time outside the home. How much time should I set aside for the cake and cupcakes? The cake will be 11" x 15" and I'm thinking a couple dozen cupcakes. It will be semi simple cake design. I'm using a picture from Fisher Prices Rain forest theme to be put on the cake along with a palm tree and a leaf motif all around the background. The cupcakes will be iced simply to coordinate with the cake colors. I don't want to make everything to far in advanced, but I also don't want to be in a hurry and not finish in time. Any and all suggestions will be greatly appreciated. Happy New Year everyone!