I can only go by the clues I find. The son of a worker (a worker involved in making poker chips) told me that his father made half a dozen chips of himself and his brothers. He dated the actual chip of himself to 1950.

I’ve heard that there may be an overlap period.

So, unless the USPC worker took a trip to Maine, I assume he made the chip at USPC, probably at night or on the weekend when the place was empty.