It's going to take longer than 1 month. You'll have some basics down, like variable scope, declaring var types, functions, etc. You might start to touch on objects.

However what are you learning C++ for? A job? A personal project? A contributor to open source software? I probably should have specified that. For a serious C++ job it'll take more than 4 months full time to be competent enough to talk your way through an interview.