For Blues’ first-round pick Robert Thomas, the feeling would come whenever he turned on the TV last season and watched Toronto, Calgary or Arizona play. Thomas’ former teammates with the London Knights of the Ontario Hockey League — Mitch Marner, Matthew Tkachuk and Christian Dvorak — were NHL rookies in 2016-17. They combined for 47 goals and 142 points as rookies with the Maple Leafs, Flames and Coyotes, respectively. “They made that jump pretty easily and pretty successfully,” Thomas said. “They all had pretty solid seasons and they all impacted their team a lot.” The takeaway was two-fold for Thomas, who the Blues took with the No. 20 pick last month. The success of his junior hockey teammates gave him confidence that he can play in the NHL, and proved by their early production, perhaps sooner than later. “It definitely does,” Thomas said after last week’s prospect camp. “There’s definitely a lot of work that has to be done to get there. But it’s nice to see that a lot of the younger guys are making it earlier. It’s cool to see that I was playing with them one year and the next year they’re all in the NHL.” The London trio wasn’t the only group of first-year players to make a good first impression last season. In the final voting for the Calder Trophy, won by Toronto’s Auston Matthews, Marner was the highest finisher among Thomas’ ex-teammates at No. 4, Tkachuk was No. 7 and Dvorak didn’t even make the Top 10. In other words, the league is now littered with youngsters who are already regulars.