"You're my best friend, Albus. And this is mayhem to the nth degree…. I am a tiny bit... scared."
-- Scorpius Malfoy (CC2.6)
Takes place early September 2020, probably during the second day after Albus and Scorpius escape from the Hogwarts Express and visit the St Oswald's Home - at the same time or shortly after the previous event
Scorpius mentions how desperate he was to go to Hogwarts and make some friends - he had a lonely time with just his parents as company while growing up (CC2.6).
From the Web
Pottermore: Harry Potter and the Cursed Child
The theatre production opened in the West End of London at the Palace Theatre on 30 July 2016, with Anthony Boyle in the role of Scorpius Malfoy and Sam Clemmett as Albus Potter: Harry Potter and the Cursed Child, Parts One and Two