The deciduous azaleas tend to keep their foliage in tufts at the end of branches. Way out with nothing in close. I agree, let it grow and establish in the pot this year. In 2 or 3 years repot again and remove all the nursery soil and replace it with your favorite bonsai mix for plants that like neutral to acid soils. I use 60% perlite (coarse, sifted, average 1/8 to 1/4 inch particle) and 40% similar size Kanuma. You could substitute pumice for perlite, and there are many good mixes that use other ingredients than Kanuma. Use what is locally available to you. Key is the mix should be coarser than one would expect if you looked at how fine the roots are. Definitely top with a layer of long fiber sphagnum to hold the soil down and keep the top layer moist for the fine surface roots. It really helps. Don't repot every year, they need a year or two in-between to grow.
Once you have a well established plant that is healthy enough to take some abuse, try a total defoliation (remove at least 90% of the foliage) after blooming, prune and wire at this time. The defoliation will help induce back budding. If you leave too many leaves, you won't get back budding and risk loosing the branches that have little or no foliage in favor of the ones that still have leaves. That is the reason to nearly totally defoliate. You can leave a few leaves on branches that are weak and you want to keep. Definitely defoliate the strongest branches. This treatment is not for every year, something you do maybe once every 5 years if you need to force back budding. If it back buds enough for your design vision without defoliation, no need to do it.
Hope that helps. I don't think deciduous azalea will tolerate laying branches down below horizontal the way a Satsuki will, they like to be upright, but your initial design heads that way, so you have a good start. Personally, I don't think heavy trunks go well with this type of azalea, so I would not shoot for a "sumo shohin" style. Hope it grows well for you.
