Hi there and welcome to the wonderful world of grooming! I would recommend NOT taking your little one to the groomer until he has had ALL his shots. Matter of fact, some of the chain stores (Pet Smart) won't even take him without all his shots. As for the "boot scootin'" this could be one of two things. There could be an anal gland problem (blockage) or sometimes I find that my male Biewer will do this simply to

"wipe his bum". I know..kinda gross...but that's what he does. Is he scootin' all the time or just after a bowel movement? Depending on when he does it may indicate if it's a problem or not. You may want to give your Vet a call and run it past them. Lastly, Yorkies need bathed weekly (with longer hair) biweekly at the longest if you keep them in a puppy cut. I tend to bath mine weekly and groom (brush/comb/topknot/teeth brushing) them daily. Good luck and enjoy your Yorkie. Daily grooming is a great time for you and your Yorkie to connect!