I had to dip back into the history cards to refresh my memory on the long, strange trip WTFM took from Long Island to the big city, and there were some pieces I'd forgotten or hadn't known.
When WGLI 1290 applied for the FM station in 1957, the application was initially filed for 105.9, which sets up a huge what-if: if the station had stuck with 105.9 in Babylon on Long Island, there obviously would not have been the 106.1 in Patchogue that became WBLI - and we'd probably now have a full class B on 105.9 in Manhattan and maybe Patchogue might have ended up with a class A on 106.3 instead.
But for whatever reason, the app was modified just two weeks after it was filed in early 1957, now specifying 103.5. WGLI-FM got its license to cover in 1958 from Babylon. It sold to Friendly Frost in 1960 and almost immediately filed for a move to the Horace Harding/LIE site. That was granted in 1961 (with some to-and-fro with the FCC over the city of license - the initial request was "New York," followed by "Flushing," and then finally "Lake Success" was what was granted.)
By then WTFM, 103.5 was on the air from the Horace Harding/LIE site in November 1961, at first with a DA to protect co-channel WPRB in Princeton, though it quickly negotiated a channel change for WPRB that moved it to 103.3 that allowed WTFM to go ND from the LIE site.
It didn't stay put there, though: the application to move to Chrysler was filed in 1965 and the move took place in 1966. Again, it required a DA to protect WPRB and WNNJ-FM on 103.7 in northwest NJ.
The next step was the move to WTC, which was applied for in 1976 and granted in 1977. I believe David's timeline is correct and that the actual move took place in 1979. It was later in the 1980s when 103.5 worked out a three-way deal with WNNJ-FM and WPRB to accept mutual interference among the stations, which finally allowed 103.5 (by then WAPP or maybe even WQHT) to go non-directional from 1WTC as a full equal to any of the best of the NYC FM signals. That agreement later allowed WKTU to be licensed at Empire as a full 6 kW class B post-9/11.
Not many other FMs can say they started outside NYC and were able to become full, uncompromised NYC signals; the only other one that comes to mind is WHTZ, though it (just like WKTU) suffers from short-spaced interference in central NJ.