The correlatives ᴹQ. imman or immanan “ever, at any time” appeared in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/109), a combination of ᴹQ. imma “any” and ᴹQ. -n(an) “time”.
Qenya
immana
any at all
imman(an)
adverb. ever, at any time
The correlative ᴹQ. immana “any at all” appeared in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/111), an adjectival form of ᴹQ. imma “any”.
Neo-Quenya: Since ᴹQ. imma “any” too closely resembles the later prefix Q. im- “same”, for purposes of Neo-Quenya I would update this to ᴺQ. aiana “any”, useable as an adjective or pronoun.