This is very important -- I don't think you should be walking him at all -- surely he is too young to have completed his vaccination series? This means until he finishes them, and you wait *another* 7-14 days, he should not ever be touching the ground outside your house as he can be susceptible to parvovirus, distemper, etc. which have a very high mortality rate in puppies. Check with your vets right away -- but usually the all-clear isn't until the puppy is 14-16 weeks or so. Carrying him is fine or bringing him over to visit people at their homes is OK, but generally you do not want to risk exposure to these very serious diseases. There are some who feel it is OK to expose puppies but I have known an awful lot of them die due to picking up parvo etc from the environment when unvaccinated or before the vax takes holkd 9the reason there are a series of vaccinations is that you don;t know when the mother's immunity wears off (from her milk) and when the vax becomes effective. If the timing is off, the vax won't do anything).
Walking three blocks for a pup that small would be very hard on his joints and is too much I think at such a youn age -- 9 weeks is really tiny -- he will get all the exercise he needs playing in your house or yard.
Check in with your vet (just give the office a ring) and they can let you know how long you need to wait. By the time his vax series is done and he is ready to go outside, he will be old enough for brief walks of 10-15 minutes, maximum, once or twice a day.
I strongly recommend harnesses, not collars, for walking cavaliers. The first reason is that small dogs can get a collapsed trachea, which is quite serious, from pulling against a collar; the second is, it is much easier to scoop a small pup to safety with a harness; the third is, this is a breed at risk of developing syrinxes in the neck area (syringomyelia) and several neurologists feel walking on collars could put pressure on the neck area that potentially can accelerate the development of them in dogs who may have them starting (research is showing about half of all cavaliers have some SM so this is an important precaution). Most puppies dislike collars at first and will scratch in annoyance at them.
In general, think of collars as the way to hold their ID tags, and harnesses for walking. You'll need a puppy size harness initially. We have lots of favourite harnesses on the board, so people will rave about the ones they like best! Many of us love Puppias.