Would you do that once there are 7-8 frames of brood in the original brood box?
Probably, but depends (as usual).
You're looking for a recipe but there are too many variables to bank on one. Open up a colony and synthesise a five-second assessment of income, colony size, weather, time of year and your familiarity with the queen, in no particular order.
I usually open up the colony and just do it on instinct because if the nest is on the up and a flow is on, they're going to need it rather than not, and as Steve said, emerging bees need space.
There are many different recipes: for example, I watched a Zoom recently where Ged Marshall described his swarm management on more than 100 colonies. Thing is, he runs on single brood boxes, so what's his trick? The most relevant factor is that he replaces queens at the end of the second year and breeds Buckfast Qs with a low swarming index.
As Q pheromone is reasonably likely to hold together one rammed box his cost/benefit analysis told him that it's an effective route. Any losses in his rural location may be picked up by bait hives. Can't recall if he clips queens.