Like all Elvish languages, the primitive precursors of Quenya appeared soon after the awakening of the Elves in Cuivienén, a period when all Elves spoke the same language. Tolkien referred to this period as Primitive Quendian or Common Quenderin [CQ]; most of the literature on Elvish uses CQ to avoid confusion with the Parmaquesta [PQ] period discussed below.

Quenya was the native language of the first and second tribes of the Elves, the Vanyar and the Noldor. This language was widely spoken in Valinor and was brought to Middle Earth by the Noldor. As Tolkien described it in the The Lord of the Rings Appendix F:

I’m starting the next phase of Eldamo Elvish-language analysis, a comprehensive survey of Quenya grammar. I’m very excited about doing this series. It is something I’ve wanted to work on for nearly a decade, but there was a lot of ground work I needed to cover first.

Version 0.7.4 of Eldamo is released. It incorporates all my recent work on Quenya phonetics.

https://eldamo.org/

Q. [w] became [v] after [l], [r]; [{lr}w] > [{lr}v]

In a discussion of Noldorin versus Vanyarin phonetic developments from the late 1950s or early 1960s (PE17/129), Tolkien said in a marginal note:

Q. final [t] became [s]; [ts] > [ss]

In the Outline of Phonology [OP2] from the 1950s, Tolkien mentioned a late Tarquesta [TQ] sound change of final -t > -s driven by euphony:

Q. exhilic [ts] became [ss]; [ts] > [ss]

In the Outline of Phonology [OP2] from the 1950s, Tolkien mentioned a late Exhilic Ñoldorin sound change of ts > ss:

but in Exhilic N. ts > ss (OP2: PE19/85).

This sound change was an addition in red ink (PE19/85 note #76), but it was also mentioned in the notes on the Feanorian Alphabet from the 1940s among “post classical” sound changes:

Q. [ɸt] became [ut]; [ɸt] > [ut]

In the Outline of Phonology [OP2] from the 1950s, Tolkien mentioned a late sound change of ꝑt [ɸt] > u̯t to form diphthongs with the preceding sound: