Although blurry, the sign can be seen directly under the Californian flag.
The
Pizza Time Theatre Winchester Restroom sign first appeared at the first Chuck E. Cheese's Pizza Time Theatre on
370 South Winchester Boulevard in San Jose, California from May 1977 to presumably the 1981 remodel.
Production
Information about the production of this sign is almost non-existent, although we can presume it may have been originally designed as early as 'The Big Cheese' restaurant floorplan creation. However, it was most likely produced from March 1977 to May 1977 pre-opening. 
Usage
Similar to many signs of the era, this sign was most likely store specific to Winchester, and was most likely put in storage or shipped to Corporate around the time of the 1981 remodel.
Design
The design of this sign is fairly bland, showcasing the white text 'RESTROOMS' in the standard Pizza Time Theatre font around the time, enclosed in a yellow border on top of a wooden board.
https://www.showbizpizza.com/info/promo/ptt/ptt_79franchise.pdf