@GrahamM - welcome to the forum.
If you could click on the icon in the command line on the upper right, you can edit your profile. If you could put your city and state and or country in the location field, you will make it easier to get location specific advice. We don't need your street address, just a location familiar enough that we can guess at your weather and climate.
Fir, genus Abies, are not used frequently for bonsai. No real reason other than most firs do not tolerate high temperatures as well as spruce. Firs tend to have smooth bark on their trunks until they have advanced age. Spruce tend to bark up at less than 15 years old.
One thing to keep in mind. Your fir has a cultivar name, 'Pyramidalis', which means this tree was created, or propagated by grafting. If you look carefully at the area below your first branch on the trunk. You will see the scar from being grafted. This means a branch or scion, from the original 'Pyramidalis' was grafted onto a piece of understock, most likely a seedling fir, it could be any fir, most conifers graft well when understock and scion are in the same Genus. A well done graft will heal to invisibility in less than 10 years or so. A poorly done graft may be an eyesore forever. Yours looks pretty good, as such I would not worry about it. If you get advice stating you have to air layer your tree to get it off the graft, ignore them. Those that would offer that advice are poorly informed and have never worked with firs. Firs in general do not air layer with any significant success rate. If you try to air layer this tree off the graft you are greater than 50% likely to kill it. Just accept the fact that the grafting scar will be there, and hope in time it will fade into invisibility.
About "Formal Upright" as a style. This is a "rule heavy" style. Going for informal upright is MUCH easier. As a formal upright, your trunk already has too many curves that will need to be straightened out. Too crooked already for formal upright. But for informal upright, you are fine.
You do not have to bring your branches to below horizontal as suggested by Sorce. That is what is often done for spruce and fir bonsai, but it is not absolutely required. Some spruces and firs do not have pendulous branches. You can train them to near horizontal or slightly rising. Key is choose the angle to be repeated through the tree. Then have all the branches on the tree repeat that angle. Branches near the bottom will be slightly lower, branches near the top should be slightly more vertical. Key is repeat the angle for the entire tree. "No piccolo players in with all the flutes." Google images of people playing both instruments, notice that if a piccolo player were standing with flute players, the instrument would be at the wrong angle, and opposite side compared to the flute players. The analogy works for trees. Usually with tree design you repeat a curve, repeat the angle of insertion for a branch joining a trunk. There is a regular rhythm to the pattern of branches in a tree.
Nice tree. If it were mine. I would do no pruning this year. I would repot into a mostly mineral based bonsai mix, in a shallow but wide grow out container. I like Anderson flats, they are heavy duty plastic, 16 x 16 x 5 inches with a mesh bottom for air movement. They hold about 3 gallons of potting media. You can use any container you want, or you can make a grow box out of scrap lumber. Key is the new container should hold as much or more media than the current pot. You are going to want to have growth in order to thicken up the trunk and have growth needed to add wood so that bends and curves will be held after styling. As to potting media, for spruce and fir I would use a mix that is at least 75% pumice. Other ingredients are not that important but the majority should be pumice, or its light weight substitute - perlite. A pumice & bark mix can work, as well as pumice & akadama. There are hundreds of bonsai media components, most can work if you understand how they affect watering and fertilizing. But if you can, find a source of pumice for yourself. It is one of the best components.
Repot this year. No pruning for 12 to 24 months after repotting. Allow recovering time.
With firs, it is best to not over work them. Until you have more experience consider the fir a one insult per year tree. Repotting is a significant insult. Pruning 10 to 25% of the foliage is a major insult. Never prune more than 25% of the green in any one year. Wiring is the least traumatic thing we do. You can prune and wire the same year, or the same time.
As you get more experience you will learn where you can push the limits. Fir and spruce tend to be trees we work hard on one day, then leave alone for one or more years, before we get back to them.