"By the time you're 40 years old, you've learned a great deal, both professionally and personally, and made a lot of mistakes. And I think respect comes with age - people take you more seriously."
It certainly worked for Johnson. It was as she was turning 40 that she set up the San Francisco-based product design company, Coupage, with her engineer husband. Business has been booming ever since.
She is not alone, it seems. Many women entrepreneurs are waiting for the right moment, and are starting their businesses in their forties or beyond - as a second or even third career - having bided their time until they are absolutely ready.
Having worked in product design and then in advertising, Raquel Johnson realised that she did not want to return to the corporate world after she had her younger daughter.
It was challenging walking away from the "sure thing" of a steady salary, she says, but she also found it liberating. She has found her "true passion," she says.
"Even the stress I feel now is more enjoyable," she explains cheerfully. "It motivates me and pushes me forward."
Starting small, the business was run from home and was self-funded at first.
"[When you are older] there is more opportunity for some savings to have accumulated," points out Johnson. "You don't have to take out large loans or search for funders right away."
Having started with a prototype for a device to integrate an iPod into a car, Coupage has grown steadily, bringing ideas to life in the fields of audio, energy, cars and Apple-related products.
"Once you reach your forties you have the confidence to follow your own path," says the US-born businesswoman, Karen Scofield, who set up her company when she was 46.
A sense of humour is also important, she adds with a smile. In the early days, she had to run her firm, London-based fashion brand Lucza, single-handedly.
It was all down to her, from technology mishaps and admin dramas to sudden, urgent errands, like dashing out to the shop to buy a copier cartridge. "Humour was definitely needed on that day," she laughs.
All of which is a far cry from her previous career as a television executive in New York, working for a smooth-running corporate machine.
When she moved to London with her husband and started a family, it was time to think again.
But the skills she had learnt in TV - time and people management, organisation, as well as research and analysis - were highly transferable, she says: Some things, however, she is doing very differently from her old workplace.
Her leadership style at Lucza is "inclusive," she says.
"But the main difference is, now you are the boss, the final decision maker, which can be daunting.
"You decide what is best and you must make these decisions with confidence." It is something she relishes.
So what advice would Karen Scofield give to other entrepreneurs when the going gets tough? "You have to push yourself forward, set your own deadlines and keep going."
The hard work and "long nights" have been worth it, she says. The Lucza brand has been increasing year-on-year sales and its pieces are worn by high-profile women such as Samantha Cameron, wife of the British Prime Minister.
She loves that her daughters see her doing something "new and scary," and adds, "I do think it's incredibly important that women support other women, however and whenever possible."
She praises The Next Women, an organisation which connects women entrepreneurs via networking events and conducts "pitch events" to prepare female entrepreneurs for fundraising pitches. Raquel Johnson found Women 2.0, which champions female tech entrepreneurs, an invaluable support
New groups are increasingly popping up such as the fledgling UK-based organisation My Next Day Job, which is collaborating with Prime, the Prince's Initiative for Mature Enterprise.
Whatever the support, however, taking this path more than half way through your working life takes confidence and bravery.
Sarah Weck of Hidden Springs Maple  - a maple syrup farm, retail website and wholesale business - was emboldened by the opportunities she saw in the market. It was too good to miss.
"Having worked in Silicon Valley I saw how retail was changing, but when I was still in my thirties the market would not have been ready for my business," she says.
The maple syrup farming business had been in her husband's family for more than 50 years, but it was Weck who, at the age of 42, decided to combine old-style Vermont with high-tech California, and sell their syrup online.
She now runs the whole operation, from bookkeeping and marketing, to payroll and even scooping ice cream at the farm shop. Her hard work has paid off - the company now has 10 employees, and sales are doubling each year.
And how does gender fit in? There are barriers, she concedes.
"As a woman, you have to make people take you seriously. Men are more prevalent in business, and women have to work at changing the image of business to be gender neutral."
But, she adds, bias can be overcome. "I've watched people shift attitudes," she says.
In the early days she was overcharged for supplies, until she proved she had researched the supply-and-demand economics for that particular season. "I'm not sure a man would have had to prove himself in the way I did."
As for her age, Weck sees it as a definite advantage. She draws on skills she learnt in her previous two careers (she was an English teacher and then a technical writer for a software company), such as leadership and attention to detail.
"I know myself and my strengths and limitations so much better than I did in my twenties and thirties."
Never a better time than in your forties, seems to be the consensus.
As Raquel Johnson of Coupage puts it: "Being comfortable in my skin has helped me be much more successful now than when I was younger and more unsure of myself. Recognising when the time is right, and seizing the opportunity is absolutely key to success."
"Timing is everything," says entrepreneur Raquel Johnson.