what's the meaning of "erst demletzt"? is "demletzt" an official word or something like a slang?

Question

Answer

It looks like a parallel to "demnächst". I've never heard the word before. It seems to be a regional word, or maybe some new creation that's slowly making its way into the general vocabulary.

http://quake.ingame.de/forum/threads/265465-wer-kennt-das-wort-quot-demletzt-quot

Some websites consider it a mistake for "letztens":
http://www.korrekturen.de/beliebte_fehler/demletzt.shtml

It's not in the Duden.

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