It will happen after the initial part of the great tribulation has passed but before the battle of Armageddon.
وَسَيَحْدُثُ ذٰلِكَ بَعْدَ بِدَايَةِ ٱلضِّيقِ ٱلْعَظِيمِ وَقَبْلَ حَرْبِ هَرْمَجِدُّونَ .‏