The power-play goal scored by Oliver Wahlstrom at 11:53 of the first period Monday was notable not for any milestone, nor even for its impact on the eventual 4-2 Islanders victory. No, this mattered because of what came before.

Ahead of the season, Wahlstrom spoke of a new mentality, saying he put too much pressure on himself last season during an abysmal second half. His playing time last year was inconsistent and so was his focus. The lead-up to Monday was the first chance this season to see whether they would lend themselves to action.

Wahlstrom hadn’t scored in eight games and his ice time had dipped under 10 minutes in three consecutive games. Coach Lane Lambert sat him during the closing stretch of games with regularity, including the last 7:09 of the third period and overtime against Columbus two days prior. It would have been easy to pout.

Instead, Wahlstrom put words to action.

“I think I’m a lot better in that situation now,” Wahlstrom told The Post on Wednesday, before the Islanders jetted to Nashville for Thursday’s match against the Predators. “Just more calm. It is what it is.

“Obviously I want to be out there, obviously I want to contribute, but at the same time, for a young player, there’s responsibilities. I’m not rushing the process right now. I’m staying in it and enjoying the process as well.”

At 22, Wahlstrom is still the youngest player on the Islanders, with five months between himself and Alexander Romanov and Noah Dobson (the members of the second defensive pair were born just a day apart). That is a fact that gets lost in the discourse around a player in his third full NHL season. So is this one: Development is rarely a straight line.

Despite that scoreless streak, Wahlstrom has nine points (five goals, four assists) in 16 games, and is scoring at nearly double the rate he did last season. It won’t all come tomorrow, but if he stays the course, there is still a lot in front of the talented youngster.

“For me, it’s just keeping a steady mind,” Wahlstrom said. “Obviously there’s gonna be frustrations within the game. It’s not letting that get to you. Being even-keeled, not too high, not too low, no matter the ice time, no matter what situations there are. Just stay level-headed.”

The message from Lambert, at least in speaking to reporters, has been one of consistent encouragement. He’d like to see Wahlstrom use his shot more, but noted Wednesday that his mentality has been in the right place

“He’s doing a very good job of just refocusing and focusing on what he can control and doing his best at that,” Lambert said. “As a result he’s having success.”

The Islanders want Wahlstrom to be a power forward who can play a heavy game and threaten opposing goaltenders. It’s not hard to see a line from there to being a consistent linemate with Mathew Barzal. And indeed, the two have been together frequently this season, outscoring opponents 8-2 at even strength, per Natural Stat Trick.

Maybe last season, when the calls from the fan base to see the two together reached a fever pitch before the pair fell flat, was too early. There will be more ups and downs to come — Wahlstrom’s development curve is far from finished — but the signs are good.

“Obviously my game’s still growing and going in the right direction,” Wahlstrom said. “A lot of veteran guys I can still lean on. For me right now, it’s just playing the right way and still leaning on guys.

“Patience is key with me. I know when I get one look in a game, it’s a high chance.”