this new programming link is great, and also the unity to ue4 is worthy to read as a start.
I have been got stuck a bit with my AI development in lite-c, C++ requires more organized work but offers more structured and flexible work. And the visual debugging possibilities of UE4 behaviour tree is really great! Of course, all the Blueprint and Behaviour Tree stuff can be later rewritten in C++ to be more efficient, but for prototyping they are awesome. When Blueprints get complex they are more difficult to look over than a well structured code package.

what I suggest is to start with the general tutorial videos:
- Introduction to the UE4 Editor

then to get a blueprint overview is very important, even if you think you don't need, only C++. they are essential to understand the engine's logic:
- UE4 Blueprint Quickshot (to see what they can do in a very short form)
- Introduction to Blueprints (gives deeper knowledge)
- Blueprint Essentials (a quick but useful feature overview)

and the 3rd person blueprint series !!! to understand how it really works, including materials, particle effects, FBX import, animation:
- Introduction to Blueprint 3rd Person Game Creation

then you can do the programming basics (which also uses blueprints), you don't really need to deal with the engine source:
- Introduction to UE4 Programming

then a good written tutorial on the Wiki:
- First Person Shooter C++ Tutorial

and a video series again to get familiar with AI made with behaviour tree and blueprint:
- AI Guard Tutorial

and if you get bored, discover the Content Examples project then you can get the source from GitHub, and go through Characted, Pawn and other important source files, to understand the whole framework's logic, when to use the Game Mode, and when AI Controller of a Character instead of directly the Character etc. it is a complex but very motivating system. after a long learning you can work faster, while in 3dgs after a short learning you need to develop your tools and framework in a more time consuming way. but if you want to make good materials in ue4, it is handy if you learn some shader programming in 3dgs.