At first, promissory notes would not be used at all because of the high barriers to entry, maintenance costs, storage costs, distribution costs, and low margins of a promissory note business.
Only coins would be used at first. Silver coins, gold coins, and hybrid coins would be used. Gold and silver content would be clearly printed on the coins.
NO fiat currency interface, NO dollar signs, and ONLY metal weight is printed on it.
For the time being, we'll have to tell merchants the value of the coin for when we use it, and they'll have to trust us and get used to the idea.
Eventually, retailers would have their own system to determine the daily gold and silver values. This is EXACTLY how currency exchange rates work.
Retailers must find their own way of determining the value of the money when they accept it, otherwise they must reject it and probably lose a customer at the same time.
That is why this must start on a small scale. We can do the same thing as local currencies have done: we start a list of businesses that accept our money and attempt to expand the list, ad infinitum.