The phrase ‘Don’t quit the day job’ is a mischievous slur on someone’s competence, but it could just as easily be a solid piece of advice for fledgling entrepreneurs. Is it feasible to work nine-to-five and create a start-up five-to-nine?

Starting a business is a notoriously risky step, mainly because founders are often left struggling financially if their idea doesn’t take off as projected. But in many cases founders have the chance to maintain income levels by remaining employed while developing a side hustle.

Before the internet era, such a strategy was frowned upon as moonlighting, but with digital communications and an increasingly entrepreneurial workforce, now it’s widely tolerated – often even encouraged. But is it a realistic route into business?

Stephanie Eltz is co-founder and CEO of Doctify, a leading review and booking service offering patients information about healthcare professionals. She started the business while working as an orthopedic surgeon, before taking a career break to focus on it full-time.

She describes taking time out as the toughest decision she ever made and says that continuing work as a medical professional helped her maintain Doctify’s relevance during its first tentative steps.

“Continuing to work as a doctor while developing the product allowed me to create something aligned with my mission to ultimately help patients,” Eltz says. “It got to the stage where the business was too large and therefore needed my full attention.

“Investors generally like it when you put all of your eggs in one basket and jump ship,” she says. “But I think this is different for a healthtech start-up, especially during the initial phase. Having an active doctor as a founder is essential to developing the right product.”

There’s a range of benefits to a two-pronged career, says Ed Johnson, co-founder of PushFar, a cloud-based platform providing mentoring and career advice. He started the business while contracting as head of digital for an antique valuations business, a role he still occupies three days a week.

He says the primary reason for staying with his employer is the avoidance of financial risk, but a close second is the love of both roles.

“Having the stability of a paid position lets me focus on PushFar’s end product, relationship-building in the HR sector and the growth of the business, without having to worry as much about my salary, paying the rent and day-to-day living,” says Johnson.

“As well as the financial stability, the things you learn from being part of a larger and more established business are very important. Working closely with my CEO has given me a lot of insight.”

There may be downsides, too. One is the challenge of staying motivated in both roles, which can be particularly tricky in the heady early days of building a business. Focusing too much on a new venture risks burning a bridge with your employer, while devoting too little time to your new business idea risks early failure.

Kerrine Bryan, founder of independent children’s publisher Butterfly Books, says burnout is another potential risk, because working around the clock leaves no room for downtime. She works in the energy industry as an electrical engineer and admits using annual leave for business meetings.

“It involves a lot of networking, various conferences, exhibitions and training,” she says. “Many of these occur during normal working hours, which meant I had to use most of my holiday days working on the business.

“There will be times when face-to-face meetings happen during nine-to-five hours as most businesses you collaborate with will run normal hours. I try to schedule multiple meetings in one day and at one location to make the best use of my time.”

Michael Foote, founder of price comparison website Quote Goat, agrees with this assessment: working evenings and weekends has eaten into his social life. But he also says clocking in for a bank while building the business helped to focus his energy.

“I found working this way to be a great motivator. The harder I worked in the evenings, the sooner I could realise my goal of working for myself,” he says. “Staying employed also offers a ‘get out of jail free’ card: if it doesn’t go to plan, there’s still a job to fall back on.”

1. Maintain standards

If you let standards slip, you could jeopardise both your career and your business, says Charles Orton-Jones, who continued working as a freelance writer while establishing the business thought-leadership platform Minutehack in 2015.

“For me, it’s important to keep hitting deadlines and ensuring that my work is high quality,” he says. “Maintaining standards is demanding, but ultimately worth it for the ‘have your cake and eat it’ set-up. Whatever you do, don’t bite the hand that feeds you,” he says.

2. Understand the effort required

Johnson advises fledgling entrepreneurs to estimate the effort it will take to succeed: “Increasingly, we see the successes of entrepreneurs through Instagram and YouTube. In some ways I think it’s now viewed as a lifestyle choice.

“Setting up a business is not easy. It’s hard, it’s tiring, but it can be hugely rewarding. Be prepared. Be certain that it’s what you want and be determined.”

3. Be realistic

An honest conversation with the boss could be the best course of action for a successful twin career. “Estimate the time commitment required to run your business and remember that you also need to eat, sleep and relax,” says Johnson.

“If it’s not viable, consider requesting a reduced working week or part-time work from your employer.”