Hello

We have just started growing a box leaf privet hedge. We've planted 100 tube stock plants, each at 25cm apart.

When should we prune them for the very first time? I've read that we should prune them early on to 'encourage bushy growth' but how early on are we talking? At the moment the plants are about 15cm high. They've pretty much doubled in size in the last 2 weeks since we planted them.