The recitation is not "Undercarriage Down" but "Undercarriage down AND LOCKED". Sometimes one tends to forget the nemonic sequence whilst waiting for the three greens and have to start again.
Comanche250 suggested lowering the gear first. I used to do this as it got the most important bit out of the way - you feel a little silly meeting the ground without wheels - and then progress to the other checks. Additionally, as the gear usually could be lowered at a speed higher than the flap extension limits, the drag was useful in getting the speed back to where you wanted it.