We begin crate training at 6 weeks of age. The pups go into the crates with their litter mates at night and we slowly start dividing the pups up into numerous crates so by the time they leave us, they have spent at least one night alone in a crate (but in the same room with the other pups). We have done the work for you so acclimating your puppy to a crate will not be a problem.
Remember to reward your puppy when he goes into his crate. When we come back from our afternoon walks, all our dogs run to their crate and wait there for us to come, close the door and give them a treat.
Your puppy’s crate is his “safe place”. Respect it and make sure young children do not tease the puppy while in his crate.