A new survey of U.S. workers from staffing firm Robert Half & Associates shows that professionals who aren't happy in a new job may jump ship more quickly than you might imagine.

According to the survey results, 28 percent of workers said they'd consider quitting within the first 90 days if they were unhappy. As companies aim to not only land but retain top talent in today's competitive market, the spotlight is shifting to employers to prove themselves upfront.

"When we traditionally talk about new employees, we usually talk about them making a good first impression," said Mike Gremmer, a regional vice president with Robert Half. "But now, with the way the talent market is, we as organizations need to make sure that we make a good impression."

Establishing a checklist for hiring managers or the person who is responsible for onboarding new employees is an important tool to make sure important details aren't forgotten, Gremmer said. It should include seemingly small details like ensuring the person's desk is clean and set up with supplies, and that his or her computer, telephone and other technology are working properly — details that 81 percent of respondents said were important to them.

Also according to the survey, 89 percent of new employees said that meeting with their manager on their first day on the job to clarify expectations was important. Additionally, 83 percent said they expected to be formally introduced to their colleagues to get their first day off to the proper start. Taking the new employee out to lunch, while a nice touch, was less important to those surveyed, with fewer than half (44 percent) saying that was necessary for a positive first day.

"I think one of the biggest mistakes is that organizations don't recognize the importance of onboarding," Gremmer said. "It's not just a one-size-fits-all type of approach; I think you have to cater it to the individual and the role. And for everyone, it's an ongoing process. It has to be a courting along the way, not just providing a great first day. That definitely helps the candidate taking the new position to feel part of the team and the culture and to feel they're making an impact."