Welcome to the world of American Flyer number roulette. According to the Greenberg guide 1216 is supposed to be the electrically powered cast iron steam engine with a headlight. In the 1918 catalog there is a head on picture of this locomotive only with the number 1225. The price lists for 1919, 1920, and 1921 calls this engine #1216 but it is not clear if this refers to the engine only or to the engine tender combination. In 1922 the price list has the engine with the headlight listed as #1216 and the one without as #1094. The same number for the engine with the headlight is listed in the 1924.
So, if yours is the earlier version this would put it at 1918. The catalog illustration for that year shows the following two sets.
I do have one question - are you sure about the spoke count. Below is a picture of the earliest version of the 1094 which has the same wheels as the earliest version of 1216. The wheels are machined steel and the spoke count is 8.