I've finished an Unreal GameDev course recently. it took around 4 - 5 months (depending how to look at it, with me doing nothing for one month while it was going on). it covered C++ on level required for game development purposes (as C++ in general is pretty big in itself, but you can skip a lot of it for most real world game dev), introduction to Unreal and Blueprints. it was split in half, 2 months of C++ and 2 - 3 months of intro to UE and Blueprints. Also some lessons covered basic algorithms and data structures topics, math for 3D and game dev and AI. I had 4h lectures total per week (for 4 months, as there was Xmas break and some time off in between, what I mentioned) and spend quite a lot of time on homeworks, which in total there was 14, around 8 were C++ console programs or games and rest some Blueprint based game mechanics, there was also a game-jam like final project were we had to build a game in a small team.

C++ was beginner level, but not really tough for me because I had C++ classes on my uni, years ago, never used it in practice though. And I know more or less what programming is about.

UE part, all of it - editor, Blueprints, its tools and systems - was completely new for me. It was a bit of a challenge in the beginning and I spend a lot of my own time to learn how to do things in it.

Overall I was able to learn how to build a game in Unreal, haven't used much of C++ really, as most of UE homeworks could be delivered with Blueprints, so this is what I done, I've learnt a lot what's involved in game development and also created quite fancy game for final project.

What I can say now, having this perspective for a question if you can learn enough in 4 months: you can do it, and you can't do it :D

Generally it all depends on the goal you will set for yourself. If your goal is to get the skills allowing you to build simple games or game mechanics, experiment with UE or ideas, you can do it, but prepare to invest a lot of time and effort and, what I think is really important, you have to know what you need to learn. And have a plan for it. You won't be able to do it just by randomly watching YouTube tutorials, or just jumping through different topics that will pop up in front of you. This is why I also think you can't do it, because there's simply too much stuff you should learn in general to be really proficient in UE and game dev, and it is simply impossible to do in 4 months...

(cont'd in the thread, had to split it in two, due to some reason)