At this point in the history of the Nephites, they must still be a relatively small population. Nephi has been both political and religious leader. However, he also appoints Jacob and Joseph to be priests. In Nephi's government, the government of God was much more important than the government of men, thus he appoints the men as priests. This may indicate a number of things. First is that while relatively small, the population had yet become much larger than at the beginning, so that there was reason for more specifically called priests.
Anthropological information: Jacob and Joseph are appointed teachers "over the land of my people." This appears to indicate that there is an established territory that they have proclaimed, and that the people are spread out on that land. This is a fairly typical ancient mode of land use. A town/city center will provide for the legal and ritual workings of the community, and there will be attached to that town center a large amount of farmland on which most of the people will live and work. Assuming that the Nephites in this first thirty years have come to the point where they will actually have a central location, Jacob and Joseph may be itinerant teachers to reach the population in the lands, rather than waiting for the people to have occasion to come to the town center.
At this point in time, the population would still probably have been insufficient to have much surplus labor, so it is probably that the town center would have mostly wood buildings. Note that Nephi's catalogue of their advances in this first thirty years does not specifically include stone masonry: "2 Ne. 5:15 And I did teach my people to build buildings, and to work in all manner of wood, and of iron, and of copper, and of brass, and of steel, and of gold, and of silver, and of precious ores, which were in great abundance." They built buildings, but the only building material mentioned is wood.
This will certainly change in the future for the Nephites, but it will take a larger population. Stone masonry takes time in the quarrying, cutting, and assembly of the buildings. All such labor removes men from the tasks in the fields, and therefore is usually associated with populations large enough to have a surplus of food that can sustain those working on the monumental projects.