Expect him to do a lot of growing until about 6 months of age, then slow down and grow in spurts from then until 18 months, or even older. A lot depends on his family. Some lines do all their growing by 6-7 months, and barely add a quarter of an inch after that. Others grows slowly but steadily after 6 months and can get their last half inch or inch between one and two years old. During major growth spurts, particularly between 6 months and a year, puppies often gain height first in the rear, so they run downhill for a while until the front end catches up.
Front feet go off, too, and often point east-west as a ballerina's.
As long as your pup started oft true, and as long as he's well-reared, his front end will eventually straighten out, but this often takes until he's over 18 months old and starting to gain muscle and broaden in chest. The same happens in the rear, but rear muscling takes even longer to develop. A 6-month old puppy should have plenty of body. But somewhere around a year old, suddenly that nice solid Beardie turns into Mr. Skin and Bones. All of this is due to the adolescent horribles which befall Beardies between one and two years of age.