On departure, the bugged airspeeds are minimum maneuvering airspeeds for a given flap setting. Typical is flaps up at V2+80, Flaps 1 at V2+60, flaps 5 at V2+40, and the takeoff is done at flaps 10 or flaps 20. Assuming a takeoff at flaps 10, the initial flap retraction to flaps 5 would take place at the bugged speed of V2+40. At that time, maneuvering is generally limited to 15 degrees of bank. At the relevant bugged speed plus 10 knots, then it's a standard bank. With flaps up at V2+80, same applies. Accelerating 10 knots above that allows for a standard bank.
The pilot flying will call for flaps up as the airspeed passes through the relevant bugged speed. Per above, as the airplane reaches V2+80, flaps up. And so on.
For approach, flaps may be selected at any time when the aircraft is below the maximum flap speed for a given setting. However, the aircraft may not be flown at a speed less than the bugged speed for that flap setting, if that level of flaps have not been selected. for example, if the policy is to land at Vref+5 as the bug setting, additional bugs are placed at 20 knot intervals above this. If Vref is 155, the bug setting at 160, then the bugs are set at intervals above that, spaced by 20 knots.
The initial flap setting can be any time below the max flap speed, but in this case one won't go below 240 knots without at least selecting flaps 1. Ordinarily this may be selected at a higher speed. When it's selected depends on what the airplane is doing, what ATC needs the airplane to do, etc. Flaps 5 is then selected at a point between max flap speed for flaps 5, and 220 knots in this case. Same for flaps 10, with the minimum speed being 200, and so on.
Different operators may have slightly different policies or SOPs on the subject, as may different pilots have slightly differing techniques.
--Let me add that I just noted you're asking about the -400. The comments above were regarding the classic. Sorry for any confusion, but it's as close as I can go.