These moments in diving, known as transitions, are crucial. They signal a changing point of the dive, and I make of point of checking with my buddy every time one of these transitions points is made. Decisions happen at transition points, and those should be shared.
This was worth repeating, I think. In cave diving, there are certain points where you always communicate with the team, just to make sure everybody's on the same wavelength and they're feeling good about the dive. But I think the same holds true for open water diving, as well. Before descent; on arrival to the bottom of the descent line, at turn, and before initiating ascent are good times to "check in", and may also be times to make sure everybody remembers the plan.