The phrase "and perhaps when he" is correct and usable in written English.
It can be used when speculating about a future event or action involving a male subject.
Example: "I wonder what he will decide, and perhaps when he finally makes his choice, we will understand his reasoning."
Alternatives: "and maybe when he" or "and possibly when he".
And perhaps when he was looking for a record deal a decade ago being posh made him an anomaly, although it certainly doesn't now, when many of Britain's leading stars, including Mumford & Sons and Florence Welch, hail from the 7% of the population who enjoyed a private education.
The ophthalmologist has suggested two additional surgeries, and perhaps when he's 18, he will need yet another operation to correct the alignment of his jaw.
When people say Carter is reckless in talking about human rights around the world, they have to remember that he trod a narrow line in the South, talking about black rights when he knew he could do very little about them--and perhaps when he did less than he might have done.
She builds a picture of Wallace as a man worn down by failure and disappointment who eventually cracked: "Perhaps when he struck the first tremendous blow that killed her, and the 10 afterwards delivered with such force, it was years of striving and constant disappointment that he was obliterating".
You never know: Perhaps when he leaves office, Mr. Obama will follow the example of Bill Clinton and flee the drama of his adoptive state altogether.
Perhaps when he was with Pop, Woody made more Jewish observations than he would otherwise.
Perhaps when he comes of age he could take up sculling, the sport of his grandfather and his Uncle Jack.
Except, perhaps, when he called Cruz a "troll" in their first debate.
Perhaps when he feels like talking in a day or two, Brodeur can answer these questions.
Did Mahler reverse his thinking at a later stage, perhaps when he corrected proofs?
His first reminiscence placed his visit in the early 1920s, perhaps when he was in his early teens.
