It takes 6-12 months to become proficient in C++/OOP. Less if the developers have easy access to a "local" body of experts, more if there isn't a "god" general purpose C++ class library available. To become one of these experts who can mentor others takes around 3 years.
Some people never make it. You don't have a chance unless you are teachable and have personal drive. As a bare minimum on "teachability," you have to be able to admit when you've are wrong. As a bare minimum on "drive," you must be willing to put in some extra hours (changing the way you think [a paradigm shift] is a LOT more painful than learning a few new facts).