A TN start gives you 100 infrastructure, which is enough to support a 1/2 million population on Luna. At that short distance civilians will happily ship over Earth's entire automatic infrastructure production, quickly ramping them up for other work. Luna also terraforms quickly, so if you don't mind spending some starting BP on a decent orbital terraforming station, you will soon have plenty of free infrastructure to seed the rest of Sol with. It is not necessary to ever build infrastructure or move colonists yourself once civilian shipping is available as you can just order existing infrastructure to be moved and they will take care of the rest.
LG infrastructure is a different story, as Earth doesn't produce any and there are no good LG seed worlds in Sol, with Vesta, Pallas, and Ceres coming the closest.