But after a strong showing for his native Czech Republic at the 2013 IIHF World Championship, he knew it was time to make the jump.
Hertl, the 17th pick of the last year's draft, signed a three-year, entry-level deal with the Sharks on Monday, and will join the team for training camp in September.
"Tomas has the tools and skill set to be an impactful player for our organization," Sharks general manager Doug Wilson said in a team-issued release. "He has been a dominant player at every level he has played at in his career thus far, including playing against players older and more physically mature than him. We are tremendously excited to have Tomas come to training camp this fall and compete for a spot on our roster."
"To play in the NHL is a dream of every young hockey player," Hertl told reporters at a press conference Tuesday in Prague. "I am very glad that my dream to sign with the Sharks has come through.
"Mentally, I am ready to take that challenge."
Hertl had 18 goals and 12 assists in 43 regular-season games with Slavia Praha in the top Czech professional league, and added eight points in 11 playoff games. But despite being held without a point in eight games at the World Championship, Hertl felt comfortable enough to believe he's ready for the NHL.
"They [Czech teammates] have told me that I don't have anything to wait for," Hertl said of the NHL. "They told me to go as soon as possible. I think the sooner I get in touch with a new environment, lifestyle, language and a different style of hockey, the better."
Hertl, 19, said his goal is to play in San Jose next season, but said if the team felt some time in the minor leagues was needed, he would go to the American Hockey League.
"They might send me to play in the AHL," Hertl said. "Players like [Jiri] Hudler or Vladimir [Sobotka] had to go through this path, too, and they've developed into regular NHL players. That might happen here, too, and I am ready to fight for my spot at the team. I hope I would get some chance to show my best hockey."
NHL.com correspondent Michael Langr contributed to this report