A study out of Canada suggests that students who put off going to college are not at a disadvantage in the job market later, as long as they complete their degrees once they start:
The researchers sought to find out if delaying post-secondary education had any effect on the labour market experiences of Canadian youth. What they discovered was that finishing a degree or diploma was more important than when it was started. [...]
The highest employment rates were found for youth who had followed the college route – either with a gap or without-and for youth who delayed university but finished a degree. Both rates were around 85 per cent. The employment rate for university graduates in the cohort who started their degree immediately was just below 80 per cent.
One possible explanation for the difference between the university graduates is that gappers may have had more opportunity to work between high school and post-secondary education and, therefore, had more work experience on their resumes.
Students who started college but dropped out — regardless of how long after high school they started — were at or below the level of high school dropouts in terms of earnings.
I suspect that there would be no difference in the results if American students were surveyed. And I suspect too that the retention rate among “gappers” might be higher than among “non-gappers”. Students who take time off to work, go into the military, etc. before entering college tend, in my experience, to have a better idea of what they want out of life and more maturity to discipline themselves to get it.