Your puppy still needs SHOTS. Be sure to get them. If he has not had a full set, he should not go out of your yard or meet other dogs until this is done.
NEVER allow your Welsh to be OFF LEAD in an unfenced area. They are very easily distracted and will chase almost anything that moves. At this point in time, their hearing is very selective, so to avoid losing your Welsh, keep him on lead.
Brush the jacket and comb the furnishing and face DAILY. Cut the nails WEEKLY. Do not bath the puppy until he is about four months old. Take a damp towel or spray him with water and rub him down with a towel to take out the dust. This applies to adult does as well. If you must bath, then limit it to the face and furnishings (legs, face and underbelly. Too much bathing only results in dry skin and coat. If you bath him all over, then make sure he is in a warm place to dry. Do not let him out in the cold until you are sure he is completely dry. To keep him tidy and comfortable, he should be clipped every six weeks to two months.
Your Welsh is a HOUSE DOG. He is NOT to be left outdoors when you are not at home either as a puppy or as an adult. Monitor his outdoor activities. Make sure he has eliminated before you allow him back in to have run of the house. Also keep in mind that a bored dog is one that barks, so do keep an eye on his outdoor activities.
EXERCISE is important. Until he is roughly one year of age, allow him to take the bulk of his exercise on his own in a run or fenced back yard. Short walks are great, but too much forced exercise on growing bones and joints is not a good idea. DO NOT exercise your Welsh beside your bike. Walk him, preferably off pavement and cement. That type of surface is hard on joints and wears down the pads on the dog's feet.
PLAY with your puppy on the floor. Until he is six to eight months of age, he should not be allowed to jump. He could break a leg, sprain a toe, or injure a growth platelet which could render him lame the rest of his life. Do not play tug of war with your puppy - it can pull the teeth out of alignment.
TOYS are important to the Welsh. Anything that is tough enough that he can't chew it to bits will do. No soft rubber or plastic toys with squeekers. He will chew them up and possibly swallow a piece that could cost you the life of your puppy at worst, or at best, a healthy vet bill to get it out of his intestine or bowel. I use home made toys that have nothing in them that can harm the puppy if it is swallowed. A knotted up old face cloth or a tennis ball in an old sock will do the trick, but again, monitor his activities with toys. If a toy is a little worse for wear, then perhaps it is ready for the trash.
Last, but not least, ANNUAL vet checks and shots are a must to protect not only your dog, but your guarantee as well.