I wanted my helmet on the Saturday I was travelling to Argentina for a polo holiday and I called the shop on Friday wanting it delivered on Saturday or for me to come to the shop on Saturday to buy. None were viable options.
I therefore agreed with the lady I spoke to that I would have two helmets (different sizes - paid for one) put aside for me in a safe place for me to come around on Saturday to try them and take away the correct fitting one whilst leaving the other.
It worked a treat.