The questions had been brewing for weeks: How long would it take the Capitals to flip the switch? How long would it take them to shake off that endless stretch when they were just killing time? How long until hockey’s best regular season team returned to its earlier form?

We now have an answer: Call it 20 minutes, give or take a few commercial breaks.

From the start of the second period Thursday night, the Capitals dominated the eighth-seeded Flyers. They knocked out one of Philadelphia’s few offensive weapons with a clean check. They dispatched another with an effective invitation to throw hands. And they left Game 1 with a 2-0 win, one little bundle of joy, which should calm thousands of fluttering Washington tummies. And all it took was one postseason visit from a longtime rival.

“We didn’t have to fake it tonight,” as Matt Niskanen put it.

After meandering through the final few weeks of the regular season — “kind of puttering around,” as one player said — the Caps had predicted early fireworks in their playoff opener. Instead, they were treated to whistles. Washington defensemen picked up three penalties in the first 15 minutes. Their second-ranked penalty kill was perfect, but the calls prevented Washington’s offensive stars from settling into the game. Alex Ovechkin has led the league in shots four years in a row; his first line didn’t generate a single shot attempt in the first period.

The slow session at least hinted at those weeks of fears: that Washington had clinched everything so early that its sharp edges would be dulled. The game’s conclusion should do away with that particular concern.

The second period brought a blizzard of offensive chances, with Ovechkin hitting a post and T.J. Oshie and Justin Williams missing on glorious power-play opportunities. Flyers center Sean Couturier exited with an upper-body injury after an Ovechkin hit, a potentially series-altering development. And Washington broke through with a John Carlson blast that traveled through and off orange-clad bodies. Shot attempts in the period? Try 29 to 18.

The final period was what you’d expect from the Caps and Flyers in the playoffs: blood on the ice, a heavyweight fight and a lot of aggressive hugging, which continued after the final horn. It’s hard to imagine, I know, but after a combined 21 penalties for 56 minutes, it seems this series might include a few raised tempers.

“That’s historically part of the Flyers,” Niskanen said. “Guys have been around. We know the tricks. If the game’s not going well, they’re going to try to do something to change the momentum.”

That backfired spectacularly for Philadelphia on this night. Tom Wilson lured 32-goal scorer Wayne Simmonds into late fisticuffs that sent both players to the showers, a trade as lopsided as Forsberg for Erat.

“It was a great job by Willy, to take one of the key players out,” Ovechkin said. “It shows character. It shows smartness.”

Add in a Jay Beagle insurance goal, and a bunch of intestinal bubbles disappeared in a shower of red antacid. Those concerns about rust, of course, were only possible because the Caps had been so dominant for so long. They had an 11-point division lead on the first day of January, a 15-point division on the first day of February, a 13-point lead on the rest of the league on the first day of March. By April, the Caps were busy convincing themselves why each game really, actually mattered.

Trying to, anyhow. Niskanen had been among the players willing to crack open the dressing room door, admitting that a team whose slot was secured couldn’t pretend its season was in the balance.

“I’m trying to be honest; I’m not trying to be negative,” Niskanen said earlier this week. “That’s what it felt like.”

With seven games to go, they clinched the best record in the league, giving them 16 days to prepare for a first-round home game. Some elements of that preparation were different from the past. Trotz suggested his staff was more restrained in delivering information than it had been last spring, an attempt to avoid “overcoaching,” or packing in too many concepts. Players said the team began tinkering with different styles of play —  different neutral-zone breakouts and forechecks — during the final weeks of the season, things that might have waited until the postseason in past years.

At the same time, they suffered one of their only on-ice slumps of the season. Washington won just two of its final seven games, a development both understandable and a bit harrowing. The Capitals had good company, as it turns out. The 2015 champion Blackhawks lost their final four games. The 2014 champion Kings lost four of their last five.

What it all meant was two months of buildup for one game, a pause that raised questions even inside the dressing room.

“I’m just curious to see how we’re going to respond now to really our first meaningful hockey game in a while,” Karl Alzner said before the game.

Thursday’s second and third periods were a comforting response. Holtby, whom the Caps call their MVP, was hardly tested but perfect when he needed to be. The Vezina Trophy frontrunner has now played in six playoff openers; he’s allowed a total of nine goals in those games. He’ll be the linchpin of any deep playoff run, among the main reasons this feels like Ovechkin’s best postseason chance.

And as they’ve done so often, the Caps pulled away at the end. Washington was 34-2-2 in the regular season when scoring first. Make it 1-0 in the playoffs.

This wasn’t the team’s finest game, but there were plenty of reassuring glimpses: Evgeny Kuznetsov was the most creative offensive player on the ice, the penalty kill continued to shine, and Washington’s superior offensive talent emerged. We wondered whether that early April puttering would continue into the postseason. It didn’t.

Now for the next question: Is there any way to build some additions onto those Verizon Center penalty boxes? Game 2 might need ’em.