There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
-llume
suffix. time, time, [ᴱQ.] times
o(na)llume
adverb. at or during exactly the same time
li(na)llume
adverb. *many a time, *many a time, often, sometimes
A correlative combination appearing as linallume or lillume in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/110), a combination of ᴹQ. li(n)- “several, many” and ᴹQ. -llume “times”.
-n(an)
suffix. time
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
The correlatives ᴹQ. ollume or onallume “at or during exactly the same time” appeared in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/100, 110), a combination of ᴹQ. on- “same” and ᴹQ. -llume “time”.
Neo-Quenya: For purposes of Neo-Quenya I would update this to ᴺQ. imallumë “at the very same time” using im- “same”.