Tolkien used a similar set of Elvish roots for “youth” and “freshness” for many years. The earliest of these was primitive guı̯u̯ or gu̯iu̯ [ᴱ√GWIWI] in the Gnomish Lexicon of the 1910s with derivatives like G. gui “just, just now, only just, already”, G. guin “recent, fresh”, and G. gwioth “youth” (GL/42). This root reappeared as ᴹ√WIR “new, fresh, young” in The Etymologies of the 1930s with variants ᴹ√WĪ and ᴹ√WIN and derivatives ᴹQ. vírie “youth” and ᴹQ. virya “fresh” (EtyAC/WIR). The ᴹ√WIN variant had derivatives ᴹQ. vinya/N. gwîn “young”. Tolkien considered, but rejected, deriving these from strengthened ᴹ√GWIN instead, producing (also rejected) ᴹQ. winya/N. bîn (EtyAC/GWIN).
Q. vinya appeared in quite a few later names with the gloss “young” or “new”, but the Sindarin form became S. gwain as in S. Narwain “January, ✱(lit.) New Fire” (LotR/1110) and S. Iarwain “Old-young” (LotR/1114; RC/128). In Definitive Linguistic Notes (DLN) from 1959, both were given as derivatives of √WIN “young” along with Q. víne/S. gwîn “youth”, though the Sindarin word for “young” was given as (archaic?) gwein (PE17/191). Also related are various words for “baby” from 1968 notes such Q. †wine/S. gwinig “little-one, baby” (VT48/6). In these notes primitive wini was glossed “little” but this was deleted (VT47/26), making it likely that the earlier senses “young, new” were restored for √WIN.
As for the 1930s root ᴹ√WIR, it might have survived as an element in the month names Q. Víressë/S. Gwirith “April” (LotR/1110), perhaps meaning “✱freshness”.
This root was established as the basis for “four” very early, though the earliest known Elvish word for “four” was actually ᴱQ. nelde from the Qenya Lexicon of the 1910s (QL/65), which became “three” later on (PE14/49). In the Gnomish Lexicon written soon after, the Gnomish word for “four” was G. cant (GL/25), and by the Early Qenya Grammar of the 1920s, the Qenya word likewise became ᴱQ. kanta “four” (PE14/49, 82). The Quenya word kept this form thereafter, and the Noldorin form became N. canad in The Etymologies of the 1930s, where the root ᴹ√KANAT “four” explicitly appeared for the first time (Ety/KÁNAT). The words and root for “four” remained the same thereafter (VT42/24-26; VT47/15-16; VT48/10), with occasional minor (and transient) variations such as √KENET (VT47/41).