I commend you for thinking about this stuff now, but there is still a number of years to go before your tree is ready to be a bonsai or bonsais. Nevertheless, thinking about the aesthetic points helps immensely with developing a plan to get there.
Indeed you want the front to present the best nebari, but it is unlikely that you are going to grow roots simply by making a little hole in the bark and stuffing it with rooting hormone. Most likely the hole will just grow closed. Nevertheless, keep this idea on your list (I too am a big fan of just finding things out). A better way is to layer the tree at some point(s) along the trunk. There is a high probability of getting roots radially all around the trunk, especially if the trunk runs (very) close to vertically at the point you cut the girdle.
Back to the design aesthetics: The basic guideline for bonsai is that one wants the trunk thickness to be something like 1/6th to 1/12th the height of the bonsai. I found this very hard to accept in the beginning, but after wasting a few years realized that violating the rule was a large part of why my trees just didn't 'work' artistically. Let's say your tree's trunk is a 1-inch caliper. The rule suggests that you should be thinking of a bonsai that is 6 inches to 1 foot tall. That is roughly halfway or all the way to your lowest branch, in my estimation.
Also, one generally should want a trunk line with movement (as opposed to a predictable, maybe straight, line). Of course, unusually arrow-straight can be cool when it is exceptional as in the formal upright style. And, of course, long skinny trunks that wander all over the place are cool too = literati, but your tree doesn't have either of these characters, though pieces of it might and/or you might grow it to be such. Lest I forget, there is also the idea of a forest or group planting. IMHO, the crappier a tree is as a stand-alone bonsai, the better suited it is to a forest/group - you just need several with different calipers.
Elms generally root well as air-layers and even as cuttings, so you could begin pursuing any one or all of these options. Personally I would be planning to make at least two air-layers next year with one girdle just above that lowest branch and another above the pair of branches that are next up. The foliage on these two branches will feed/drive rooting of the lowest girdle and that lowest branch will be feeding the roots that keep the whole tree going. There is some interesting movement just above that branch pair, so you might choose a point a little higher instead, so that the trunk section above has some interesting movement. Before the end of the 2022 growing season I should have at least three separate trees, two of which have new air-layer roots. The following spring (2023) I would repot them (removing sphagnum if that was used) after removing the branch stubs below and screwing them onto a board/tile (which will help to make nice nebari). Likely later in the season (2023) I would trim back their initial surge of growth (June-ish) and will try to root those cuttings. Otherwise, I'm just tending to their needs (the original trunk piece and two layers as well as the cuttings) while just letting them all grow (bigger).
There are resources and threads on air-layering here on BNut as well as many discussions of rooting cuttings (cmeg1 is doing some interesting stuff with rooting cuttings that you may want to try).
Then I would be re-evaluating my desires and what comes next. Do I want to ground layer the bottom trunk piece? Has I sprouted below that one branch? Being so straight it might make into a good broom-style tree. Do I want a shohin broom or do I want to keep growing it to make something bigger? Do I just want to chop it down and see what happens (elms are pretty good in this regard)? Do I have decent radial roots on the two (or more) air layers? Do any of them seem to offer something interesting that I want to spend 5 more years pursuing? If yes, what and make a plan to get there. If no, maybe make a group/forest planting and see how it goes (it can always be disassembled sometime into the future). Yada, yada, yada. This is the fun!
enjoy