As per the email you received when you placed your order:

REGARDING MODIFICATIONS: When I receive an order, even though the ship date seems far off (in practice, I often ship early), work begins on your ring immediately. Within 48 hours, the metal for your ring has very likely already been ordered, and perhaps has already been completed. For this reason, if you need to make a change (size, width, etc.) AFTER 48 hours, there will be a charge of $30.