If eight months — nine seasons, really — can come down to a single act on a sheet of ice, then Hudson Fasching’s moment came Wednesday night, all that work and toil balled up and the result playing out in front of 17,255 people.

The Islanders were coming to the end of the first period night and the air had briefly left UBS Arena.

Just over a minute earlier, the Canadiens had tied the score in a game the Islanders had to win to clinch a playoff berth without help.

The puck fell to Fasching after Zach Parise’s shot, and the 27-year-old Minnesotan took a whack at it.

That whack gave the Islanders the lead and they did not relinquish it in a 4-2 victory that secured a Stanley Cup playoff spot.

“Pretty surreal,” Fasching told The Post in the postgame locker room. “Hard to believe. I’m obviously ecstatic. It’s a dream come true.

“It’s something every kid imagines, playing in the Stanley Cup playoffs. Absolutely excited, thrilled.”

Much as Fasching might have imagined such a moment as a child, he would have given you a more realistic assessment eight months ago, when the Islanders signed him to a two-way deal after his eight years with the Buffalo and Arizona organizations had yielded just 38 NHL games, one NHL goal and a lot of AHL bus rides.

“I wouldn’t [have] believed you, probably, I guess? Obviously you gotta believe in yourself,” Fasching said, “but to some extent, it’s hard to believe. I’m just really happy to be here, grateful for us.”

Fasching’s goal on Wednesday was his 10th of the season, as he continued to play a vital role on the third line. Thrust into the lineup in December amid a slew of injuries, Fasching never left — and as a pending free agent this summer, he is suddenly a priority.

“Obviously,” Fasching said prior to the game, “I’d like to stay here.”

The Islanders should like to keep him.

Anders Lee, who had met Fasching during occasional summer skates back in their home state of Minnesota prior to the season, understands the grind well as a former sixth-round pick who made it. These moments don’t come often. Fasching seized his.

“This game is, at times, very unforgiving,” Lee said. “But he’s had an opportunity this year and you have to take advantage of it.

“This league is extremely tough. You kinda have to have results or make an impact every night. There’s no question he’s done that and more. So I’m extremely proud of him.”

Fasching doesn’t use the word “proud” much, though he surely does feel some pride in this most unlikely achievement. He usually opts for “grateful” — and gratitude did emanate from him Wednesday night.

“I think staying in the NHL is coming to some sort of a stable position,” he said, “but playoffs is a whole other element and something I’m excited to tackle. But yeah, it’s pretty crazy.”