Andrew Lee hasn't graduated from college yet, but he's already a hot commodity for recruiters in the tech sector. The 21-year-old Stanford senior majoring in computer science is not so much hunting for jobs as employers are  hunting for him. Or, rather, they're hunting for people like him -- young, promising engineers.

It's now October. Lee graduates in June. He's already interviewing with major public tech companies like Google, Amazon and Twitter, in addition to startups such as local services marketplace Thumbtack, valued at $1.3 billion, where he's spending this particular Friday for interviews and recruitment activities. At the big public companies, there's stability; but at startups, there's a chance to be more involved and make a greater impact, says Lee.

Attracting talent is an increasing challenge for startups in the Bay Area. Ali Behnam, managing partner of recruitment firm Riviera Partners, says competition for engineers is being fed not just by growth among startups and public tech companies, but relatively new interest among non-tech companies in the same talent pool. Banks, credit card companies, manufacturers and other established businesses that once felt comfortable in industries now being disrupted are vying for the interest of young engineers in hopes of catching up to the pace of Silicon Valley.

"There's intense competition for talent. I don't think that there's anybody who would deny that trend," says Behnam. "I mean, we're just seeing the competition increase every year because we're seeing non-tech companies trying to hire as well."

Startups have to take a more aggressive approach to recruitment as they grow, but that doesn't mean they're doing anything out of the ordinary to spark the interest of college seniors.  Thumbtack, for example, does all the usual things startups do to find undergrad talent, such as holding hackathons on campuses and taking part in career fairs.

 What's new is that the company is making university recruitment a year-round endeavor, says Thumbtack university recruiter Dayna Cano. (The company recruits more experience candidates year-round as well.) Thumbtack focuses efforts on Stanford, UC Berkeley and MIT, though the startup will of course consider applications from students at other schools where the company has less of a presence.

The goal is to turn year-round recruitment into an institutionalized, repeatable process, says CEO Marco Zappacosta. The company needs a scalable, systemized approach because its previous ad hoc efforts are no longer sufficient. Thumbtack reports its staff has doubled each year since 2012 and the company hopes to continue this growth. Its San Francisco headquarters now hosts 150 full-time employees. "The biggest difference is just the focus on scale, and that the processes and the methods you put in place when trying to hire a handful don't work when you're trying to hire 30-plus people a quarter," says Zappacosta.

Behnam says recruitment activity is busiest in the fall, around October, and in the spring. For Thumbtack, October is the sweet spot for recruitment activity. A few factors contribute to the primacy of this month: Students are still settling into classes in September, ruling the earlier month out; a lot of college seniors studying engineering decide where they'll work or intern before the time the spring semester starts; and in November and December, many are too busy preparing for exams or with holiday travel to focus on job hunting.

The company decided to go hard on October this year, interviewing up to 10 candidates on site each Friday of that month plus a few during the week. The reason for choosing Fridays is that more students have a break from classes at the end of the week. The startup also changed its "family dinner" night, when employees have the option of inviting family and friends to gather for a home-style meal prepared by the startup's staff chefs, from Wednesdays to Thursdays. Again, the idea was to accommodate student schedules -- Thursday nights are more likely to be free from major assignments.

Dinners and lunch on interview days might include informal "non-evaluative" conversations between prospective new engineers and staff. Visiting Thumbtack when candidates are on site, you would think the startup was applying to hire the college students rather than the students applying for jobs.

Startups begin unknown, so they still have to pitch themselves, explains president and cofounder Jonathan Swanson. "I think for the very best talent there's a lot of competition," he says. One day when the company has a million users, it won't need to rev up recruits with the founding story.

Until then, Thumbtack is doing what it can to establish itself on the radars of engineers like Stanford senior Lee, ultimately offered a job by the company. Lee first encountered Thumbtack at a career fair on campus, and the Friday he visited the startup, he seemed to be very seriously considering it as a place to launch his career upon graduating. The college senior described the perks of working for the unicorn as falling somewhere between those of a scrappy startup and tech megalith.

"It's pretty stable, but it's also very exciting," he said of the company. He may still have time to make his decision: As of earlier this month, most university candidates were still within a decision-making window established by their schools.

Thumbtack has its own approach for recruiting the talent it needs to grow, which can in some ways be replicated. For companies struggling with talent acquisition, Behnam has a few tips:

Broaden the pool of schools. Stanford, UC Berkeley, Cornell, UCLA and University of Waterloo produce the most-hired candidates according to Riviera. Behnam thinks a number of colleges are neglected or under-rated by Silicon Valley, among them Carnegie Mellon, Cal Poly, Johns Hopkins, Georgia Institute of Tech.

Look at older developers. Saying "older" may sound funny, considering the word can simply mean "old enough to drink" in Silicon Valley. The point is, while recent college graduates may have experience with new languages or techniques, experience still matters. Engineers who have been around can mentor recent grads. 

Look outside your industry. You don't have to hire developers with experience in exactly what your company does. Uber can hire developers from the world of fintech and it could work out great, says Behnam.