I'll be honest: can't think of a state-maintained California freeway that did not get a number after the Signed State Routes came into existence, and certainly way before the 1964 Great Renumbering. The names may have been in primary currency but virtually everything had a US shield or state shield at that point.
SR 103 around San Diego (now SR 15 and I-15) is shown unsigned on official maps until 1969.
As a UCR student at the time who made regular trips to San Diego, the first time I saw signage for CA 103 was in the fall of 1968, about the time that DOH was signing many previously-unsigned routes, including CA 83 on Euclid Ave. in Ontario and Upland and the parallel CA 31 on Milliken Avenue (later superseded by I-15); about that time the original CA 67 signage on the northeasternmost portion of the "Helix Freeway" (mostly CA 94 from I-5 east) was replaced by the signage for CA 125. Also, in SD, CA 209 received signage about that time from I-5 to Point Loma. The actual deployment of signage varied from district to district; D9, east of the Sierra, was the first to feature signage of every route within its jurisdiction, including CA's 182, 167, 158, 203, 168, and 136, all unsigned before 1967 (the signed reroute of CA 190 to Olancha occurred that year as well). Signing efforts within D11 and D5, flanking L.A. along the coast, proceeded from the summer through the end of 1968; this included the CA 217 UCSB access freeway. D7 in metro L.A. lagged a bit behind, with effective completion in the spring of 1969 -- although they did decline to sign some routes they considered nonessential, like CA 187 and CA 213; signages for both of those occurred in the mid-'80's. What was interesting is that the "if we own it, we sign it" edict came down in early 1967 immediately after the (Reagan) gubernatorial change. But both D6 and D10 in the Valley had begun to sign some of their previously unsigned routes prior to that; CA 137 received signage in early 1965, followed by CA 155 a year later after the alignment change into Delano from the original Oildale routing. The shorter unsigned routes in the Visalia-Kingsburg area (CA 216, CA 201) happened in mid-1968, about the same time their counterparts in D5 were being signed. But by the beginning of 1970 just about every existing mile of state highway, urban or rural, featured at least rudimentary reassurance signage.