The term "top hoodlum" was in use by FBI offices before the Apalachin meeting, and a Top Hoodlum Program - seeking to identify local underworld leaders - may have been in place from the early 1950s. FBI itself reported that a Top Hoodlum Program of sorts was put in place on August 25, 1953, in response to a New York office request that Washington share its accumulated information on gangsters within the New York territory. (see the archived FBI webpage: https://www.fbi.gov/page2/august07/mobintel080907.htm ). Certainly, local offices conducted pre-Apalachin investigations of Mafiosi and labeled some of them "top hoodlums."
I'm not sure that this early activity is of major importance to a discussion of "The Top Hoodlum Program" directed specifically against U.S. Mafiosi. And FBI seems to have backed away from its comments about the (largely inconsequential) 1953 program. Note that in a timeline of FBI history on the current FBI.gov website there is no mention of that program and the timeline specifically states that "Director Hoover instituted the Top Hoodlum program" following the Apalachin conference of November 14, 1957 (see: https://www.fbi.gov/history/timeline ).
FBI's investigation of organized crime as a national conspiracy apparently was initiated through a "Top Hoodlum Program, Anti-Racketeering" letter dated November 27, 1957 - less than two weeks after Apalachin. This letter, officially recognizing that organized criminals and their rackets were not confined to separate regions of the country, provided for greater coordination of efforts from FBI offices and the deliberate investigation of Mafiosi around the country as members of a single criminal entity.
Within the November 27 letter, all offices were instructed to forward photographs and vital data on regional top hoodlums to the New York office. This was noted in a January 16, 1958, memorandum. The memorandum suggests that photos of as many as 250 top hoodlums already had been collected (see: https://www.maryferrell.org/showDoc.htm ... 2&tab=page )
The program also appears to have set a quota on the number of top hoodlums to be designated by each regional office. In February 1958, when the Salt Lake City office sought to make Lester Binion an informant, the office was instructed: "They must submit another individual in his place in connection with the Top Hoodlum Program" (see: https://www.maryferrell.org/showDoc.htm ... 4&tab=page ).
The program set in motion by the November 27, 1957, letter was referred to in FBI reports for several years. (for example, see: https://www.maryferrell.org/showDoc.htm ... ,%20a-r%22 )
By the way, the often repeated claim that FBI did not have the authority to investigate and arrest interstate racketeers before Apalachin has no basis in fact. And FBI did investigate and in some cases wiretap racketeers before the 1957 Top Hoodlum Program was in place - documents show that some earlier surveillance info was incorporated into Chicago's post-1957 Top Hoodlum Program dispatches. (FBI's ability to wiretap anyone it wished to wiretap was not seriously limited until the 1960s. And FBI frequently proved that it would do whatever it was moved to do unless specifically prohibited by law.) It could take action against organized criminals involved in bank robberies, prostitution, kidnappings, hijacking, hired killings, obstruction of justice, union extortion, corruption, transportation of stolen goods and other crimes (even racketeering conspiracy - a federal offense charged against Chicago bosses in the 1940s!). Narcotics trafficking was also already a federal crime, under the jurisdiction of the Federal Bureau of Narcotics. Various forms of counterfeiting were within the jurisdiction of the U.S. Secret Service.
It did not initially have tools to attack the mechanisms of communication (closely related to gambling rackets) and gambling-related transportation among racketeers. The 1961 laws known as ITAR (this abbreviation more recently has been assigned to arms trafficking), ITWI and ITWP addressed these gambling-related shortcomings, but FBI did not require these laws to take action against many rackets and racketeers.
The intent and extent of the original Top Hoodlum Program is questionable. There is little doubt that the program was energized in late November of 1957, following Apalachin revelations which were as embarrassing for FBI as they were for organized crime. Even then, the aim of the program remained vague into the next decade.
I am still working my way through Gage's book. So far, there seems little of unique value in its discussion of Hoover's early work against organized crime. If you're interested in giving the book a look, here's a link:
G-Man: J. Edgar Hoover and the Making of the American Century by Beverly Gage.