Regarding this issue, Dr. Marawan Shahin, Professor of Hadith and its Sciences, said that ‘After `Isha’, one may find some Muslims offering the two supererogatory rak`a of `Isha’. Then, one may find them offering tarawih Prayers as much as each person can do. So, a Muslim may find some people offering four rak`a or more of tarawih or qiyam individually before the commencement of the congregational Prayer of tarawih and there is nothing  wrong in that.

It goes without saying that the Prophet performed tarawih Prayer individually and in congregation and so both ways are correct.

May Allah accept our good deeds from us.