If it says please make an appointment one day in advance, you should make an appointment in advance, at least the day before. If you go on the day of purchase, the store will not receive you. If you don't come to make an appointment in a hurry, you can call the store first and ask if you can go on the same day. Some things that are not so strict can be (rarely). If you can, you can go back to the store. If not, don't go there, so you can save a trip in vain. It is safer to do so ~ ~