I remember the little evergreens beside each fw on many courses. Also a few plates in the ground, usually only at 150 back then, expanded to 100, 150, 175, 200, 225, and sometimes comically, "Forgetaboutit" later on.
When I was lucky enough to play Medinah (circa 1967) they had notations on the back of the scorecard, telling distances from this tree or that (and the trees had an X, or small metal dot, etc. so you could tell (usually) one tree from another among their then 20,000+ trees. (We were hired one winter to count them, LOL, a nice little side biz for northern architects without much going on) Anyway, attempts at marking yardages were in place then.
The first time I saw a course measured for plates on the sprinkler heads was in 1984, my inaugural year in my own biz. I redid a few greens for Jim Colbert when he ran the Vegas Muni, and they were putting the yardages on all the sprinklers there. I presumed it was a trend started somewhere on Tour that Jim thought should have filtered down.