How long does it take to make/order an edible picture cake?!?!?!?

I'm somewhat organizing a surprise party for my 'boyfriend' (it's a long story) See...I was going to decorate his locker and do all this cool stuff and I was going to do it with my two best friends: Katie and Jonah (who is also his best friend). What I was going to do is take a picture of me, Katie, and Jonah then take it to a bakery so they could make the super awesome edible cake things. Then put "Happy Birthday, from your secret admirers" next to the picture. Although, I'm not sure how long it'll take for the bakery to make it. I just want to know if it's going to be like an "It'll be done by tomorrow thing" or more like an "It'll be done next week" thing. Sorry, this is WAY more detailed then it needs to be. Please help!