The Bombers booted 13 goals to four after half-time, as they thumped the Dogs by 55 points.
"I'm not sure what to think just yet," Hird said after the game. "It's a pretty hectic couple of hours.
"Certainly very happy with the way our boys played. I think the improvement over the pre-season has been excellent and the way the boys played, they did a lot of things right.
"Was it was I expected? I didn't know what to expect. I think going into round one, every coach isn't sure how your team has prepared.
"For myself and the coaching group, some of us hadn't done it before, and we hadn't with this group before.
"But obviously we're very happy with what happened."
While the atmosphere in the Bombers' rooms was understandably buoyant, Hird was doing his bit to keep a lid on things.
"We're very conscious that the Essendon footy club, I reckon, hasn't handled big or good wins that well," he said.
"Even in my day, we'd have a couple of wins and the club would get really excited and then you'd have a couple of big losses.
"It's one win, our first win for the year. We've got a very tough football team next week, in the Sydney Swans in Sydney, so we can't afford to get carried away.
"Yes, we've won a game of football and the boys have played well. But that doesn't make our season."
Essendon dominated the Bulldogs in the middle of the ground, with skipper Jobe Watson (35 possessions) and fellow on-baller Heath Hocking particularly effective.
"We don't have a Chris Judd, a Gary Ablett, a Cooney in our midfield," Hird said.
"But we've got a group of guys that want to work hard and are desperate to learn how to be really good footballers. I think today they were very good."
The unheralded Hocking, who was second in the Bombers' best and fairest last year, accumulated 27 touches, which included 13 contested possessions and 11 clearances.
Dashing defender Courtenay Dempsey also impressed the coach.
"We had a few words after the NAB Cup grand final about the way he performed," Hird said.
"He came back today was really, really good and showed the sort of character we want from Courtenay Dempsey. He deserves a big tick for the way he played today."
Ruckman David Hille, who battled knee problems during much of the pre-season, was another outstanding contributor.
"For Tommy Bellchambers not to play was very hard on Tom," Hird said of the young ruckman pushed out of the team to make way for Hille.
"[It's hard] to go to a guy after he's had a terrific pre-season and say 'you're not playing' and we're going to back Hilley.
"It was a risk. We didn't how Hilley would go and whether he'd get through a full game.
"But to perform the way he performed was exceptional and it just shows the quality of player that he is."
