Families lined up outside Brooklyn Technical High School on Saturday to enter the city's annual high school fair.

The city’s high school admissions process definitely seems more complex and competitive since Sergio Coria went through it 20 years ago.

Corio made the observation after spending more than four hours at the Citywide High School Fair at Brooklyn Technical High School on Sunday with his 13-year-old sister, Nicole.

“It’s a good eye-opener to see how many students you are competing with,” Sergio said about the fair, which more than 30,000 people attended over two days. “It’s a wake-up call on what you need to do and how you need to do it — you definitely can’t wait until the last minute.”

Nicole had already identified about a dozen schools in the city’s high school directory that seemed to speak to her interests in art, math, and science. But she said narrowing down her choices hadn’t yet given her much piece of mind.

“It’s scary: You don’t know if you’re going to get accepted, and then once you get there you don’t know if you’ll like the teachers,” she said.

Plus, Nicole said, she was nervous about heading off to high school without her best friends, who unlike her were shooting for specialized schools and selective music schools. “It’s kind of sad because I’ve been with them so long,” she said.

One consideration that Nicole won’t have to make, according to Sergio, is about her commute. Any good school is an option, even if it means a lot of travel time, he said.

“Some families like to be nearby to where they live, but I think a commute is a good idea,” Sergio said.  “That’s the way you’re going to get mature – by traveling on your own and developing city smarts.”

For Karida Ali, on the other hand, the entire high school search might come down to commute time.

The Richmond Hill eighth-grader currently attends York Early College Academy in Queens, which goes through high school, but is considering schools in other boroughs. Her mom, Zabeida Ali, thinks that’s an ill-advised plan.

“In terms of travel time, is it really worth it?” to make the move, asked Zabeida Ali, who said older daughter, now in college, skipped the citywide fair in favor of a Queens-only high school fair. The city does not allow students to transfer high schools because of travel time unless their commute is longer than 90 minutes each way.

Karida has a guaranteed spot to stay at York Early College Academy if she ranks it as her first choice. But she wants to try her luck at the city’s most selective schools, the specialized high schools that include Stuyvesant High Schools and Bronx High School of Science.

Karida’s ambition has started a bit of an argument with her mom, who would rather she stay at York, where she can earn college credits and graduate with a two-year associates degree.

But Karida said she was not deterred and would be sitting for the Specialized High Schools Admissions Test next month. “I just want to experience taking the specialized high school test and see where it goes from there,” she said, adding that she is focused now on studying for the test.

Attending the high school fair was a way to gather backup options for Anthony Rivera, as well. The eighth-grader currently attends a Catholic school, but he’s also seeking scholarships to private high schools and looking at science-themed public schools, too.

But along with his mother, Anabelle, and his younger sister Nicole, Anthony said he found the fair overwhelming and hard to navigate.

“It’s kind of a mob in there,” he said.

So the family opted just to puck up materials from science and engineering schools and listen to the principals’ and students’ pitches, but not ask any of their questions. That will happen at the individual schools’ open houses, they said.

“I hope the open house will be more calm, less people, and that we’ll have more of a chance to talk,” Anabelle said.

But she said she was glad the family had made it out to the fair nonetheless, because now they’ll have a head start when Nicole goes through the process in two years. “We’re here looking for him, but at the same time we’re keeping an eye out for her too,” she said.

The Mendez family from Far Rockaway, Queens, was also laying groundwork for a future high school search. Father Marvin brought 10-year-old Jadon along with Zakiyah, who is in eighth-grade now.

Zakiyah said she wants to go to a school close to home that has a strong writing program. She focused on talking to current students while her father took down hard details about each school, including their progress report scores and student-to-teacher ratios.

After checking out a bunch of schools, Zakiya identified the Academy of Finance and and Enterprise as an early favorite. “They’ll help us create our own business and they do community service,” she said. “I would start a fashion business.”