Jazz went for the first time at about 8/9 months old.
As there hair grows it will be fluffy, and they will start to lose puppy fluff.
Its really good pratice, to start them getting used to it, now, but putting them on a secure table with a non slip surface, and using the brush. The more you pratice this the better, it will make life easier for you.
Put it this way, i never did it with Jazz enough, and now I can't get her to stand stil for me when I am holding a brush.
Providing you are firm, and make them sit, or stand, it will mean you can brush and trim a bit as you go along. If I so much as get the scissors out, she starts sreeching, and running around.. But I did nip her a while back. SHE HATES ME !!