Robin Hill Nursery has been breeding azaleas for many years, it is not a Satsuki, it is a USA origin hybrid, but it does have some Satsuki in its ancestry. They should be fully winter hardy in your area, which is good. The flowers will be fairly large, likely 2 to 4 inches across. Think of your branches as display platforms for the flowers, for 3 inch flowers you need to leave space, at least 3 inches between two branches on the same side of the cascading trunk or there won't be room for the flowers. If you end up with branches and inch apart on the trunk you will have to alternate between the different directions so one branch does not end up too close directly over another branch. Or you can do a smaller design where the branches radiate out, and there is never one branch above the other, In an upright this would be a variation on the informal broom styles or clump styles. For a cascade, make sure your tiers of branches are far enough apart.
I would just let it grow for the remainder of this year. I have a cascading Satsuki, and cascades in general are a unique learning experience. Even though most azaleas are not considered "apically dominant", they don't necessarily make easy cascade subjects. The problem you will constantly have is branches that sprout along the cascading trunk, the upper branches will be stronger and try to "outgrow" the lower branches. For my own cascade, I prune the upper branches back hard, to just a leaf or two per branch, the middle section I will leaves longer branches when I prune and the lowest portion often will go without being pruned at all if it has not outgrown its shape. The lowest part will be slower growing. The upper branches you might have to prune 3 times to every once you prune the lower.
Right now the first branch on your cascading branch should be cut back to just one or two leaves, it is monopolizing the energy coming down the cascading trunk. You want the lower branches to grow more. Cut back the uppermost branch now, and you will probably have to cut it again later in summer. Let the bottom most grow without pruning for the rest of the year. Anytime the branches higher up get more than an two to four inches longer than the branches on the lowest point, consider pruning the upper ones back, unless your design plan needs a longer upper branches. One common design, for cascades is the lower the branches are on the cascading trunk, the wider they flare out from the cascading trunk. There are other designs, but if you have no plan, you can start with this and over time come up with your own design.
Right now, you don't have many branches coming off your cascading trunk, but by end of summer you should have several dozen branches bud out on the cascading trunk. You will want to keep the same pattern on the cascading trunk as you would on an upright trunk, left-right-front-left-right-front, etc. You want a 3 dimensional arrangement of secondary branches. Keep them coming out bending down, then up at the ends of the branches. No branches going directly toward the pot. The very end of the cascade should turn up a little bit. All branch ends should turn up a little at the very end. You might not need wire to do this, azalea will naturally grow upwards. You will need to wire branches downward.
If you feel ready to try your hand at wire, wire the cascading trunk to work in a bit of movement, give it a "wiggle". Right now it is rather straight, it will be easiest to wire now while young and somewhat flexible, before many new branch buds have sprouted. By next year it may be too stiff and woody to bend easily. Be careful, azalea wood is very brittle and snaps easily. If you are not ready to try your hand at wiring, don't worry, there are things later you can do to create movement down the road.
