The oval window didn't come out until mid-1929 to dress up the otherwise drab Business Coupe. Note that the wheels and tires have been changed to 19" from a '30-31 Model A.
Marshall
The 54A Business Coupe (with oval window) went into production in 1928. Knocked-down body kits were being shipped out of the USA in 1928. I do not know when the 54A initially went on sale in the USA.