Usage of "next to" with dates and time periods

In sentence of form

Something must be reported prior to the first working day next to the reporting month.

does "next to" strictly means "after reporting month" or it can be treated as one before the reporting month?

I'd also like to know is it valid to use "next to" idiom with date/time periods, and have some examples of proper usage. Or may be this sentence can be rephrased in more comprehensible way?

In this case, "next to" is awkward because dates are not physically next to each other. It does imply that, looking at a calendar, you need to count to the next day.

The other problem here is it's vague. It could mean the last working day of the month previous to the due date, or it could mean the first working day of the month after. If I had to guess, I would say it's the latter, since making something due before the month it's due makes little sense.

If we're going for clarity, I would phrase it as

Something must be reported by the first working day after the reporting month.

If the report is due in October, it has to be submitted no later than the first working day in November.