When to do a crown reduction on mature beech tree?

Hi all

I just bought a house with some pretty big beech trees very close to it and had a tree surgeon do a report.
He advises around 4m crown reduction on two trees ( they are around 25 metres tall ) and suggested doing it at the end of June.
I did ask about nesting birds but he said he wouldnt expect the 2 trees to have nests.
Informed opinions much appreciated.
Thanks in advance