You should wait until after they bloom before pruning. This years flower buds were produced last year and removing the tips of the branches will remove them. Wait until they bloom and then prune them as soon afterward as possible.
New growth will appear after pruning and next years flower buds will be produced then.
Rb

Here is a link that might be useful: Azalea Care

Thank you- I intend to cut some Delaware Valley Whites back to within a foot of the ground. They look so bad that I have not cared much if they were lost. I'll give them one more chance. Maybe next year I can make a picture of some pretty flowers.

Supposedly August is the cut off date. Any pruning should be done between after the time the azaleas bloom and August to have a bloom the following spring.

I cut back some of mine, the tops were badly damaged in the freeze, but they were blooming at the bottom. I was planning on cutting them back after the bloom, so I did it now so I could at least see the little bloom I had.

BTW, azaleas usually go through a 'molting' period of leaves after blooming and look like hell. That plus the freeze we had are making all azaleas look pretty bad this year. They should start to put on new leaves in a few weeks.

Many of our azaleas look really bad because of the freeze. But the Delaware Valleys are so straggley looking and are in dire need of renewing. Most of the azaleas have spread a lot- I had no idea they would root at the ends of branches and form new plants like they have. Our back lot is beginning to look like a jungle. Anyone wanting to increase their plants don't have to go to the trouble of rooting cuttings in pots. Just make sure branch tips are in the mulch and they'll root.

Don't forget to fertilize after blooming also.