No, you can't customize your box before signing up. Once you complete the sign up process, we'll let you know when your first delivery is scheduled and your customization window. If your customization window is open at this time, you can customize right away! If it's not open yet, you can see when it will open here.
Since we can't show you our inventory, we have instead included a list of items that are generally available during summer to give you an idea of what to expect.