When and how do I trim a newly planted 6ft pot grown privet hedging?
What height do you want to stop it at? Established privet usually needs trimming every 6 weeks or so throughout the summer, so you can prune it whenever you like, assuming there are no birds nesting in it. Only a light prune is needed using either shears or electric hedge trimmer. It needs regular watering of course for the rest of this year until it gets established (or you have lots of rain!).
North East Somerset - Clay soil over limestone