On the modern Boeings (737) you get an instant indication of the detent position the flap lever has been PLACED IN by the appearance of the speed on the speed tape - once the lever is in the Flap 5 detent for example the "5" speed appears on the speed tape and so on.
My company has the SOP on extension of PM only calling the Flap when the indicator shows the flaps have reached the commanded position.