C++ seems like an awfully steep climb for someone that age with no experience. I'm not sure what educational resources are available directed at that age.
I'd suggest that you start out with something more forgiving. Python has been a pretty good choice and has an OO core without quite so many "guns, knives, and clubs" which was an original description of the difference between Java and C++.
Most important, however, is that there are materials available for both Python and Java that are directed at younger learners.
In Java, for instance, the Greenfoot system provides a graphical system that provides both a visual environment and a fairly strong programming support environment that is amenable to younger learners.
I don't know of anything quite comparable in Python, but there may be some things.
One of the things that you might want to think about is that a new learner doesn't need to start with a bare screen and no support, building everything as they go. Virtual worlds can be constructed, by teachers or authors, that enable a beginner to do interesting things much earlier than they can if they just start by learning int variables and
if statements. If you spend all of your time learning syntax and low level ideas you may not get to do anything interesting and so get bored easily. Better in many ways to work in and modify an existing system (in well considered ways) than to have to build up from nothing.