Sometimes, Nica Yusay's online vintage purse store, FashioNica, sells out so quickly that she thinks there's a glitch on her website.

A lifelong thrifting enthusiast, Yusay developed a talent for finding high-end purses at a fraction of their retail value from a young age. She accumulated her own collection over the years, but never thought she could make money from her skill — until her fiancé suggested she make a business out of it.

In January 2021, Yusay took the jump, spending $15,000 on luxury purses she intended to resell on sites like Poshmark and Depop. She also posted a video on TikTok about negotiating prices with customers, which went viral: Yusay says she gained 10,000 followers almost immediately. The video now has nearly three million views.

After six months of growing interest, Yusay created a Shopify website for FashioNica. By the end of the year, she'd made $300,000 from the side hustle — enough to convince her to leave her $82,000 annual salary as a digital marketing brand manager for Pieology Pizzeria in February, and pursue FashioNica full-time from her home in California.

The Fenti-toting influencer — who has 137,000 followers on Instagram and 115,000 on TikTok — says the leap was "extremely scary," especially considering how much she spent on initial inventory. "I think it comes from [growing up in] a single parent household. I felt financially insecure," Yusay tells CNBC Make It. "This is not a stable job in any way. If you don't even sell one bag, you made zero dollars this week."

FashioNica has brought in roughly $1 million in revenue since 2022 started, according to documents reviewed by CNBC Make It. The business earns up to $55,000 on each drop.

Here's how Yusay manages her six-figure business, and where she plans to take it next:

A regimented routine

The secret to Yusay's sustained sales is a strict schedule. She usually works six days per week, all leading up to "drops" when she releases a new batch of 20 to 30 designer bags, on Wednesdays at 7 p.m PT. The bags sell for anywhere from $170 to nearly $19,000 each.

Drops can sell out within two minutes, Yusay says — and getting to that point takes nearly a week of preparation.

"You'd think it would be easier once you start working full time, as opposed to having two jobs. But no, I'm so strict on myself," Yusay says. "If I wasn't super dedicated, this business wouldn't be where it is today."

On a typical Monday, Yusay decides which bags will be included in the upcoming drop. She spends hours photographing them for her Shopify website and social media accounts. On Tuesdays, she posts the photos and writes the product descriptions.

Wednesdays are spent preparing for the drop and marketing the bags on Instagram Live. Yusay spends Thursdays at thrift stores and with her vendors, sourcing unique bags. Fridays are dedicated to shipping labels and managing her Instagram inbox.

On Saturdays, Yusay packs and ships out orders. She usually takes Sundays off.

In March, Yusay hired her mother and sister to help her with the shipping process — helping her claw some of her time on Saturdays back. But she says she doesn't plan to use the extra time to rest.

"I was thinking, 'if I was to, hire my mom and my sister, for example, and have them ship out my orders, I would gain a full day,'" Yusay says. "A full day could mean I can add an additional five, maybe even 10 bags to my inventory for the next drop."

Selling her way up in a cutthroat industry

The luxury goods secondhand market had an estimated value of $33 billion in 2021, according to management consulting firm Bain & Company. One popular luxury resale vendor, The RealReal, reported almost $1.5 billion in 2021 sales.

Yusay's plan to stay relevant in such a large cutthroat industry: Keep hustling and using her well-trained eye to find purses that'll stand out from the crowd. She says she looks for bag styles that have stood the test of time: Some of the items in her inventory are up to 30 years old.

For now, Yusay says she wants to add more purses to her weekly drops, hire more employees and eventually move FashioNica into its own facility.

"I would love to get to a place where, in like five years, I can say I have a whole team helping me out [in] a warehouse," she says. "I'll have an actual brand that's outside of my house."

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