Azaleas (pruning and fertilizer)
When is the best time to fertilize, and then to prune?
Fertilizing is often not required if you mulch regularly, but you may do so in early spring if you are noticing deficiencies. Pruning them can be done anytime between the time that the old blossoms fall off and the new start to grow.
This article will give you more information: https://www.gardeningknowhow.com/ornamental/shrubs/azalea/azaleas-noteworthy-shrubs-for-any-garden.htm