The CW’s “The Flash” is gearing up for its final season, and with it, series star Grant Gustin is looking back.In an Instagram post he shared late Tuesday night, the actor, who has played Barry Allen/The Flash across eight seasons of “The Flash” and the season before on “Arrow” (when the show was introduced as a backdoor pilot) shared a short note with fans looking back ahead of Season 9.“Tomorrow we start filming the final season of ‘The Flash.’ I’ll save the long, emotional captions for later in the season, but to say I’m grateful for this journey and the growth it’s provided me in so many different ways would be a gross understatement,” Gustin shared. “Thankful to everyone who helped give me this opportunity and all the fans of the show that have showed me and anyone that’s been a part of ‘The Flash’ love along the way.