Theoretically, the dog should have already been startedon this. a good breeder of dogs that will need to be groomed a lot should already be aclimating them to the process wehn they have them. I used to work for a poodle breeder. when their eyes opened, she started training them on the table, and geting them used to being handled. by 4-5 weeks, they go in for their first "haircut" (clean face, feet, tail). by the time they go to their homes, they are perfect for grooming, and can handle a full groom. every single dog i have ever done who was started on grooming from a young age has been perfect.
if the dog came from a less than reputable breeder, or a shelter, then this things obviously didnt happen.
Start NOW! put him a table of sorts (a washer/dryer works well too), and handle him. pick up his foot, dont put it down until he lets u hold it without struggling. brush him. make him stand still. hold his face. all of these things will help him get used to what he has to do at the groomer.