"On the first [blank; sic] of every month, ..."
Is the implied word of the blank in the demonstrated beginning of the sentence fairly clear? Feel free to comment your interpretation of the word and its reason. (This poll already assumes you have a reasonable command of English.)
I'm just here to see the results.25%
Yes, the implied word is quite clear regardless of context.0%
No, the implied word depends on context.75%