When should the one who wants to observe I'tikaf enter his place of I'tikaf?

'A'isha (Allah be pleased with her) reported that when the Messenger of Allah ﷺ decided to observe i'tikaf, he prayed in the morning and then went to the place of his i'tikaf, and he commanded that a tent should be pitched for him, and it was pitched. He (once) decided to observe i'tikaf in the last ten days of Ramadan. Zainab (the wife of the Holy Prophet) commanded that a tent should be pitched for her. It was pitched accordingly. And some other wives of Allah's Apostle ﷺ commanded that tents should be pitched for them too. And they were pitched. When the Messenger of Allah (may peace he upon him) offered the morning prayer, he looked and found (so many) tents. Thereupon he said: What is this virtue that these (ladies) have decided to acquire? He commanded his tent to be struck and abandoned i'tikaf in the month of Ramadan and postponed it to the first ten days of Shawwal.

حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا أَبُو مُعَاوِيَةَ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ عَمْرَةَ، عَنْ عَائِشَةَ، - رضى الله عنها - قَالَتْ كَانَ رَسُولُ اللَّهِ ﷺ إِذَا أَرَادَ أَنْ يَعْتَكِفَ صَلَّى الْفَجْرَ ثُمَّ دَخَلَ مُعْتَكَفَهُ وَإِنَّهُ أَمَرَ بِخِبَائِهِ فَضُرِبَ أَرَادَ الاِعْتِكَافَ فِي الْعَشْرِ الأَوَاخِرِ مِنْ رَمَضَانَ فَأَمَرَتْ زَيْنَبُ بِخِبَائِهَا فَضُرِبَ وَأَمَرَ غَيْرُهَا مِنْ أَزْوَاجِ النَّبِيِّ ﷺ بِخِبَائِهِ فَضُرِبَ فَلَمَّا صَلَّى رَسُولُ اللَّهِ ﷺ الْفَجْرَ نَظَرَ فَإِذَا الأَخْبِيَةُ فَقَالَ " آلْبِرَّ تُرِدْنَ " . فَأَمَرَ بِخِبَائِهِ فَقُوِّضَ وَتَرَكَ الاِعْتِكَافَ فِي شَهْرِ رَمَضَانَ حَتَّى اعْتَكَفَ فِي الْعَشْرِ الأَوَّلِ مِنْ شَوَّالٍ .