Pruning Dwarf Lilac Bushes
How and when do I prune dwarf lilac bushes?
Certified GKH Gardening Expert
While these wouldn't require as much in the way of pruning as larger varieties, the times and techiniques would be similar to them. Here is an article that you may find helpful: https://www.gardeningknowhow.com/ornamental/shrubs/lilac/pruning-lilac-bushes-when-to-trim-lilac-bushes.htm