It is unwise to come to the gas and start with powerful robber engines. It throws on its back, the inexperience of the motorcycle passes longer than the car. It is a summary of the experiences of experienced bikers.
To get started, first forget the engines above 250cc. No matter, with good education and plenty of practice in a good institution, I will curl this business, I am already a driver of years, my reflexes are like a cat, etc. Do not fool yourself by making sentences like, because a motorcycle is not related to cars or bicycles. Institutions that already provide good training will not tell you different sentences, on top of that, if you state that you buy a motor above 250cc, they will ask you where you bought it and deal with the seller company (yes, there is an unwritten tradesman ethic such as not selling engines above 250cc to new starters). Absolutely get training not only from your relatives but also from educational institutions and practice in areas that are mostly closed to traffic.