When people meet your 6 month old kitten, they may be shocked that it's still a baby! Maine Coons start to level out somewhere between 9-14 months; though still growing the maturation process slows and they fill out more subtly until the age of 4 or 5 years.
Some people are confused about the coat as well, as many Maine Coon cats seen in the show hall appear to have a mostly short coat, with some length and fluff around the belly and britches, and may have no noticeable ruff. These will generally be your younger adults and seen in Championship, which are cats that have not been altered. Some Maine Coons will never grow a full and luxurious coat until they have been either spayed or neutered. MC's may also vary on when they grow their "seasonal" coat, often known as full coat. Logic would suggest they be in full coat over the colder winter months, but this is not always the case. Some cats look like a domestic short hair with excess belly fur all winter and grow a long lustrous coat in May, while others are mostly bald until November when they look like they're ready to face the arctic!
At what age your Maine Coon kitten starts to grow it's shaggy coat can vary greatly. Some kittens develop coat almost immediately and look like miniature MC adults at 3 or 4 months, while others will start getting britches and belly fur around 6 months and a ruff will start to fill in as late as 1 year, provided the kitten has been altered before 8 months of age.
Do not be concerned if your cat doesn't look like a Maine Coon all at once. The variations of growth patterns are as varied as they are among different families of humans. No, not all MC's will look the same, but the classic shaggy coat, square muzzle and big expressive eyes will all come together eventually, the cat will be your loving and ever-present companion! You may be initially attracted to the Maine Coon for their rugged good looks, but you'll fall in love with the personality.