The phrase "a stage when it" is correct and usable in written English.
It can be used to describe a specific point in a process or development when something occurs or changes.
Example: "We are currently at a stage when it is crucial to evaluate our progress and make necessary adjustments."
Alternatives: "a point when it" or "a phase when it".
"I came into it at a stage when it was about the art, the artists," she said.
The student orally presents and defends the thesis work in progress at a stage when it is one-half to two-thirds complete.
Embryonic stem cells are taken from the embryo at a stage when it is a hollow sphere consisting of a thousand or so cells.
And so, after too many nights watching movies alone, I steeled myself to let friends fix me up at a stage when it felt like my teenagers' turn to tiptoe into the uncertain world of romance, not mine.
Among How To Get Rich's quotes read out to the tribunal was this: "By the time talent is in its mid to late forties or early fifties, it will have become very, very expensive... it will reach a stage when it is being paid based on past reputation alone.
Such awards offset the loss of clinical income during a stage when it is critical to spend maximal time in research in order to establish an independent career.
At such an early stage of one's career, "it's hard to have something to show," he points out, and the EMBO award is "a level of distinction" one can get at a very early stage in one's career--a stage when it is really needed.
Ignoring an issue at a nascent stage when it shows symptoms of a larger crisis can cost us too much.
The fear for Israel is that such repeated attacks may only invite Hezbollah - backed by Iran and the Syrian government - to ignite the Golan front at a later stage, when it is in a suitable position to do so.
You could be mistaking atheism as a permanent stage, when it is really a temporary transition from one faith to the next.
After hatching from an egg, the woolly adelgid goes through a crawler stage, when it moves around.
