The phrase "a time when professionals" is correct and usable in written English.
It can be used to refer to a specific period or occasion involving professionals in a particular context or situation.
Example: "There was a time when professionals in the industry gathered annually to share their insights and experiences."
Alternatives: "an era when experts" or "a period when specialists".
So-called "conversion therapy" or "reparative therapy" began at a time when professionals in medicine and psychology considered homosexuality an illness that was amenable to treatment.
Even his small telescope could show up a great deal of detail on the moon's surface, making it especially attractive to amateur astronomers at a time when professionals tended to neglect it.
A time when professionals break away from their fifteen-hour workday to play dress-up, just like the characters they create and portray, and perform for the world.
Health professionals may have concerns about the very notion of self-management and its aim of encouraging patients' autonomy and control over their health and health care at a time when professionals are increasingly accountable for disease outcomes and adherence to evidence based guidelines.
Likewise important, he introduced a female actor in the leading role in his film Bhasmasur Mohini (1913) at a time when professional acting was taboo for women.
At a time when professional football, baseball and hockey players are eliminating war analogies in conversations, Hopkins refused to back away from his metaphor.
Mr. Gross, a former marketing executive at 20th Century Fox, started Movie Review Intelligence in 2009, at a time when professional film critics, threatened by layoffs and newspaper closings, were thought by some to be a vanishing breed.
All this in a season awash in reality-television freak shows, in an era where some Nascar fans favor crashes over races and in a time when professional wrestling is more and more about slam-bang swagger.
Using some 200 objects, many dating from the late 16th and early 17th century, the exhibition seeks to conjure up London as it was when Shakespeare was a dramatist at the Globe theatre at a time when professional playwrights were a new phenomenon.
