I am kind of in the same boat. Realistically, you’re not going to get up and running in a day or two. It’s going to take a few weeks to really get familiar with the engine and its back end architecture. Fortunately for you, you’ve got lots of experience with making games, programming, and a game engine, so a lot of the concepts won’t be lost on you.
I wrote up my game prototype in C# using XNA, and now I’m in the process of porting it over to UE4. It’s going to take a while, but fortunately I’m not in the awkward position of trying to figure out what kind of game I want to make and trying to learn a new tech at the same time. What’s been really helpful for me is the C++ code tutorial series they posted. It gives you a taste of how the workflow should go between C++ and blueprints and they leave the rest up to you to figure out and implement. It’s a great launching point. There’s a plethora of documentation out there, so it’s mostly a matter of trying to figure out “I’m trying to do X, how do I do that in UE4?”. I recommend following the TutorialCode tutorial series. Follow it step by step and try to understand what each line of code is doing and how they interact with the editor and blueprints. (They also use GameMode code to implement some game logic).
As far as backend architecture goes, getting a good grasp of the class inheritance hierarchy is pretty important too. From what I understand, it goes something like this:
UObject -> Pawn -> Actor -> Character
One slightly annoying but necessary thing about coding in UE4 is that they don’t let you use the C++ int keyword. Instead, you have to use their keywords like uint8, uint32, int32, etc. But, if you expose some of those variables to the detail editor, they’re grayed out (such as int32, but not uint8). I’m still new to the editor as well, but I haven’t figured out how to use restrictions on property values either, so if you have 8 players max and you want to create some sort of editor control to set that restriction… I don’t know how to do it, yet.
Anyways, there’s lots of resources out there in the forms of documentation, youtube videos, content examples, forum posts, etc. Just manage your expectations a bit and you’ll be fine. It’s going to take some work to get proficient, but it’s certainly a lot faster than writing your own engine from scratch again.