L.A.-based indie pop band Phases seems to have cracked the code to a successful Coachella debut: low expectations. Slotted into the first spot on Saturday, often reserved for lesser-known bands, I was so resigned to [think] like there’s not going to be anyone here. It’s just going to be us. It’s going to be fine. Whatever,” said frontwoman Z Berg, née Elizabeth Anne Berg, as she kicked back at The Retreat at the Korakia Pensione in Palm Springs on Sunday. “Then I got onstage and there were so many people. They were so psyched. There were so many bros, and it was, like, perfect sound, perfect set,” she said. “We had the luxury of playing first on our stage, so we got there and had a leisurely sound check. Playing early is a really wonderful experience. Highly recommend it,” added Berg, who was wearing a low-cut gold dress, part of her Coachella-inspired capsule collection with Christy Dawn. “I realized it’s very convenient to design things because then you just have s–t to wear,” deadpanned Berg, who counts Olympia Le Tan and Saint Laurent as her favorite fashion brands.

The 29-year-old, immersed in the music scene from a young age thanks to her father, former Geffen Records A&R executive/record producer Tony Berg, first played the festival with her former group, The Like, a decade ago. Her bandmates Jason Boesel, Michael Runion and Alex Greenwald (whose significant other is Brie Larson) also performed on the Empire Polo Field grounds during their stints with other bands. But this was their first time they took the Coachella stage together in their newest incarnation.

Years ago, the longtime friends decided to form a band called JJAMZ during a “fateful” overbooked karaoke night at Guy’s bar in Los Angeles. “We couldn’t sing, which is why we left and started our own band. It was like, ‘We can just do karaoke at home,’” Berg explained. But when the side project turned into a full-time job, James Valentine, lead guitarist for Maroon 5, dropped out. “Once this became a real band and also we signed to another major label, Interscope was like, ‘You can’t do that, sorry!’”

Their first post-Valentine move: trading in JJAMZ, an amalgamation of their first initials, for Phases, a moniker inspired by their new manager. “She said, ‘I love your record so much. Every time I listen to it I’m just transported back to being a teenager in the mid-Eighties and going to this underage dance club in Canoga Park called Phases.’ And we were like, ‘Check please! I’ll take it,’” Berg recalled with a laugh.

Phases released their debut album “For Life,” last year, which was heavily influenced by jamming out to Michael Jackson’s “Thriller” album on their tour bus. “We sort of tried to re-create in my lo-fi studio what they were doing for ‘Thriller,’ which was some drum machines, live drums here and there, keyboards, bass, all this kind of stuff,” said Greenwald, former member of garage rock band Phantom Planet, of recording sessions in his living room. Added Runion of the evolution of their sound, “JJAMZ had more of an indie rock lean. This has more of a dance-pop lean. Wistful funk if you will.”

Next up: A show at The Roxy on May 18, a tour with fellow indie band Saint Motel, and — in a full-circle moment — touring with Maroon 5 in the fall, a chance for the band to reunite with Valentine.

But for now, they’re just trying to survive their collective lack of sleep, a product of staying out late at a friend’s get-together, not indulging in the after-hours desert party scene. “Well, see, I’ve learned. F–k going to Coachella after parties. I don’t ever want to wait in line for anything ever, and I don’t want to see any strangers or any people who I’ll run into after Coachella,” Berg said. With one notable exception: “You know who I met yesterday was f–king Wolf Alice, who I love, and who are the nicest people in the world.”