Wikipedia isso fica claro em c.3 anos desde que o S1 inicia no 1977 e o S2 inicia no 1980.
Vemos Holden dando palestras na Academia do FBI, pouco antes de ingressar na BSU em agosto 1977.
Season one is set in 1977—in the early days of criminal psychology and criminal profiling at the Federal Bureau of Investigation[6]—Mindhunter revolves around FBI agents Holden Ford (Jonathan Groff) and Bill Tench (Holt McCallany), along with psychologist Wendy Carr (Anna Torv), who originate the FBI's Behavioral Science Unit within the Training Division at the FBI Academy in Quantico, Virginia. They interview imprisoned serial killers in order to understand how they think, with the hope of applying this knowledge to solve ongoing cases.
Season two is set between 1980–81 and covers the Atlanta murders of 1979–81.[8]
Quanto à "brecha" entre o S1 e o S2, provavelmente não passa de um longo fim de semana e parece que o ataque de pânico sofrido por Holden estava atrasado na semana anterior.
Vemos Holden recuperando a consciência no hospital imediatamente após o ataque de pânico.