Exactly how many years does it take to master the reading of the Qur'an in the seven or ten qira'at?

Question
As-salamu 'ailakum wa rahmatullahi wa barakatuhu,
   Exactly how many years does it take to master the reading of the Qur'an in the seven or ten qira'at? Also, is it required for a qari to master only seven qira'at or ten?
Answer
Wa alaikum assalam wa rahmatullahi wa barkaatuh
There is no set period of time to master the qira'aat.  Most scholars or shuyookh require memorization of the Shaatibiyyah poem for the seven qira'aat and also the Durrah poem for the three qira'aat to complete the ten.  The time taken depends on the students abilities and ambitions and the teachers time.  It takes years though, not months.
It is not required to learn all ten at once.  Once can learn the seven (or fewer) and then if they wish, later learn the three others from the Durrah, to complete the ten.