Khadija died three years before the Prophet ﷺ departed to Medina. He stayed there for two years or so and then he married ʿAisha when she was a girl of six years of age, and he consumed that marriage when she was nine years old.
تُوُفِّيَتْ خَدِيجَةُ قَبْلَ مَخْرَجِ النَّبِيِّ ﷺ إِلَى الْمَدِينَةِ بِثَلاَثِ سِنِينَ فَلَبِثَ سَنَتَيْنِ أَوْ قَرِيبًا مِنْ ذَلِكَ وَنَكَحَ عَائِشَةَ وَهْىَ بِنْتُ سِتِّ سِنِينَ ثُمَّ بَنَى بِهَا وَهْىَ بِنْتُ تِسْعِ سِنِينَ
[Machine] The Prophet ﷺ married her before leaving Mecca for Medina, when she was three years old, or close to that. He consummated the marriage when she was six years old. After his arrival in Medina and when she was nine years old, he built a marital relationship with her.
أَنَّ النَّبِيَّ ﷺ «تَزَوَّجَهَا قَبْلَ مَخْرَجِهِ مِنْ مَكَّةَ بِثَلَاثِ سِنِينَ أَوْ قَرِيبًا مِنْ ذَلِكَ وَنَكَحَهَا وَهِيَ بِنْتُ سِتِّ سِنِينَ ثُمَّ بَنَى بِهَا بَعْدَ مَقْدَمِهِ الْمَدِينَةَ وَهِيَ يَوْمَ بِنَائِهَا بِنْتُ تِسْعٍ»