Best time of year to do it, they are being planted on built up ground as well so their feet won’t be too wet over winter, a couple of years ago they got a grant to make a small woodland, they wanted us to do it but had to have someone like natural England to do it, they did it in late spring, 90% are dead, where as the hedge I planted for them in the November is now 3’ high and ready to be cut back
I did this one 3 years ago same time of year and never had to replace any