Study / Academic year start and end months in Poland English medium schools [8]

Hi All,
I am from India and planning to take up 1 to 2 year work assignment in Poznan. I would like to know, when does the academic year start and end in poznan / Poland English medium schools?

International School of Poznań is what I have in mind..any reviews or better English medium schools in Poznan ?
Two Kids of age 8 years and 4 years for Primary Years Programme(PYP)