Conqueror can have them prebuilt when you start the game but if you mean going to an empty settlement, selecting a plan and have it all done within a minute I’m pretty sure that’s not going to happen. I don’t use city plans (Id rather control what is built where) but I remember when I tried them that even just cleaning and building the base (level 0) took some time which, if I’m not mistaken, is why SS starts the “flying while watching it build” thing it does.
From there level to level takes some time (which I’m guessing is what you want to disappear) and potentially time to accumulate the necessary scraps (that can already be turned off). The time restraint seems to be a design decision (it’s there for plots, city plans) and at this point I’d be surprised if they removed it entirely, even if optional. Keep in mind I’m not working on the mod, it’s simply an educated guess. Because some time constraint (that can happen while you are away) combined to the pre-build settlements from conqueror makes me doubt they’ll change it. But I’ve been wrong before.
PS: Just in case your issue is with the fact that things can take a few minutes to be finished, I have some bad news. The game will always have limitations and it takes time for things to be done. As an example, if you start a new game with conqueror and pre-build settlements and use a fast start mod it might cause issues because SS uses the time you’d normally do the intro to build settlements and it could be a long process depending on how many settlements (and the complexity of the plans themselves I assume). That period of time that makes things not build instantly will never go away completely, it’s part of the limitations. Kinggath and company didn’t just decide to make people wait 5 minutes cause they think it’s funny.