The situation isn't so that we first had a theory of capitalism and then went to implement it.

No, partially it was actually done that way. https://en.wikipedia.org/wiki/The_Great_Transformation_(book)

Polanyi argues that many traditional, NON-ideological, but more like evolved local custom types of restrictions (i.e. Burkean conservative restrictions) on the operation of the free market were removed by government action to pave the way for the market, in an ideological hope that it will enrich society (it did, but anyway).

(Take it with a grain of salt, though, Polanyi had strong socialist sentiments, even marrying in the communist movement. Not to be confused with his bro, Michael Polanyi, who generally had libertarian leanings.)