When ordering a cake (or any product, actually), be clear about when the cake needs to be picked up.
Clients tend to talk to the baker in terms of what day the party will be. "We're having a party on Sunday ....." Bakers tend to listen to the conversation for a clue on when the cake is needed. "She needs the cake on Sunday." Confusion takes places when the client arrives on Saturday to pick up the cake (that she needs tomorrow) and finds the cake isn't ready. The baker is confused because her order form says the cake isn't due until Sunday.
Party Time and Pick-up Time are not the same thing. Both parties need to be clear on when the item is needed. I'm going to put the weight on the shoulder of the baker and suggest the business should have a place on the order form for day and time of PICK UP (or delivery).
The best phrasing isn't "When do you need the cake?" (they NEED it on Sunday for the party). What SHOULD be asked is "What day and time will you pick this up?" For some bakers/bakeries, there may be a specific window of time for order pickups in which case the baker should let the client know, "Your cake can be picked up on Saturday between 2 and 4."
It works the other way also, with clients who do things at the last minute. I had a client who was planning a Sunday party. I asked her "What time on Saturday do you want to pick it up?" She reminded me, "Oh the party isn't until Sunday."
I said, "I'm closed on Sunday. What time on Saturday do you want to pick it up?"
She said, "I didn't really want to pick it up before Sunday."
I said, "I'm closed on Sunday. What time on Saturday do you want to pick it up?"In this world of 24/7 everything where nothing needs planned ahead and people are used to picking up things "on the way" to an event, details like pick up times need to be clearly stated up front so both parties understand what is expected from the other.