In fact, more often than not, it shouldn't be measured in days, but rather in hours…. Most of the personnel could already start doing their jobs adequately on their first day, it might not be perfect, but with the assistance of machinery, the rough form wouldn't be too off.
That was the situation of the current era. Experts would be trained from a young age if they showed any affinity for space, and by the Golden Core Stage, with the assistance or artifacts and careful material selection, they could start creating Spatial Devices. Of course, for them, they couldn't just bind the space to their person, as their person wasn't strong enough and would be burdened by the space. They also couldn't bind it to a simple stone or anything they wanted, as their fundamental level of control wasn't great enough, and they needed quality material or formations to help guide them.
