Very lightly if at all right now they are trying to get established and too much pruning will encourage top growth instead of roots

I agree with the light pruning, it is very important to let the boxwoods establish. When you do get to pruning avoid using shears of any kind, the best pruning is with handsnips. It takes more time but allows for a better look for the plants and allows for better health for the plants. Make sure to deadwood the boxwoods seasonally and clean up leaves from under the plants as often as needed (boxwoods drop their leaves two times per growing season)

The link below shows what hand pruning looks like: