The phrase "a few instances when" is grammatically correct and can be used in written English.
It is typically used to introduce specific examples or occasions when something happened or occurred. Example: There have been a few instances when I have forgotten my keys and had to call a locksmith to let me into my house.
But there are a few instances when bulb planting has been disappointing.
One instructor, Sarah Grimaud, said she knew of a few instances when Ms. Kay spoke of his problems with epilepsy.
There have been only a few instances when people have objected to his performing at a college.
There were missed shots and turnovers at crucial junctures — and a few instances when pump fakes sent Robinson flying wildly by.
Although he said there have been a few instances when high school students were caught drinking at G.W., he would not comment on how the specific situations were addressed.
There have been a few instances when my instructions for "two dots over the 'i' " have been transcribed as three dots over the "i," which is cute but wrong.
I also had a generous friend, Kyeong-soo, to consult in those few instances when even the internet drew a blank.
It will be one of the few instances when the absence of an asterisk next to an alternate's Pro Bowl accolade is actually justified.
There are few instances when the world provides a perfect metaphor, so we should be grateful for two books being released to mark the occasion: My Father at 100, by Reagan's biological son, Ron, a prominent liberal radio host and avowed atheist, and The New Reagan Revolution, by Reagan's adopted son, Michael, himself a radio host and political strategist for the Christian Right.
As scientists, there are remarkably few instances when we would think a single measurement or count is 'the truth'.
The decision, by a largely party line vote of 213 to 197, is one of the few instances when Democrats have been willing to buck the White House on a matter of national security.
