I don't know how many are familiar with this old Latinized method of abbreviating dates. It was widely used in English until, I think, early in the 20th century:

Ultimo etc.

Was anything like this ever used in early Esperanto? Something like la 25-a pasinte, la 11-a proksime, la 17-a aktuale?

Not an answer to your question but just a side note. In Spanish you still use this convention in correspondence. Pasado, corriente and próximo for last, current and next month.

nornen:Not an answer to your question but just a side note. In Spanish you still use this convention in correspondence. Pasado, corriente and próximo for last, current and next month.

That's interesting to know, since it's considered quite obsolete in English.

Maybe more reason for Esperanto to have it, if only to translate more literally from Spanish and any other language that has it.

Bruso:

nornen:Not an answer to your question but just a side note. In Spanish you still use this convention in correspondence. Pasado, corriente and próximo for last, current and next month.

That's interesting to know, since it's considered quite obsolete in English.

Maybe more reason for Esperanto to have it, if only to translate more literally from Spanish and any other language that has it.

A more "literal" translation would not be preferred, in this instance, in my opinion, because it would impede the ability of the meaning to be understood by Esperantists from different language backgrounds. Sure, someone may be able to deduce from context that when you say "aktuale" you mean "this month" as opposed to the word's actual definition ("present day" or "currently"}, but if others can't reliably understand it, what's the point?

ESPECIALLY because there are Esperanto words that can be formed easily from roots that convey those meanings far more universally and specifically than vague expressions like that. I have no idea how/whether this was done historically, but you can use "pasintmonate," "ĉi-monate," and "venontmonate," if you're set on finding one word equivalents. These are all used with "semajne" to refer to relative weeks, so I see no reason why they can't be used for months as well. As they more accurately express the intention of the speaker rather than translating what appears to be a somewhat idiomatic usage, I feel that they would work better.