Agreed with Jared here totally.
Start with blueprints, when you get hang on blueprint communication, api function names, how stuff works, you can start with small things, like translating some most intense loop from blueprints into C++. Or making some utility blueprints instead of macros.
For eg my game happens on “orbit” (no real Kepler mechanics, just sphere around planet). So every time i want to move “left or right” i get right vector multiply it by some distance. But that introduces some “drift” of distance from center, so i need to snap back my location. First i made macro for doing this (it was all over my blueprints), but someday it became first piece of code i translated into C++ in unreal. It uses just few variables and returns single vector.