Your answer is how I initially interpreted the rules.
I think my source of confusion was looking at historical contracts data offered by Quandl. For gold, there are only eight months per year available all the way back to 1975. The webpage says gold only trades on GHJKMQVZ months; January contracts don't exist.
Wikivest on the otherhand says gold trades every month of the year.
Not 100% sure (without actual accurate data) that there's a January month. Would some one knowledgable (who either trades gold or has accurate data) let me know if gold has a January contract? If so, Quandl has more missing data than I believed. (It could also be that I'm getting contract names and exchanges mixed up. Quandl's gold data has the ticker symbol GC and is labeled "CME gold futures". Historical data for individual gold contracts from COMEX exist but show up as a blank page, so I thought they must have been moved to the CME gold futures page.)
There is a contract for every month including January. Below is the daily chart for QGCF14 from IQFeed. Unless you are involved with spreads or delivery then you should only be trading G, J, M, Q and Z.
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