Q.Pruning Lilac After Major Renovation
I have renovated an overgrown Lilac, cutting back two main trunks to about a foot off ground level. I staggered the work over two years. I now have a very healthy looking shrub which stands about 6 ft. No flowers this year, but I wasn’t really expecting any. I would like to keep the plant around its present height, but not sure how to proceed with regards to pruning / thinning, and when would be the right time to do this. Any advice would be gratefully received. Thank you in advance.

Certified GKH Gardening Expert
Sure, here are some articles that will help you:
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/lilac-bush-not-blooming.htm