The Sunnah on the day of sacrifice is to stone the Jamrah, then offer the sacrifice, then shave the head, and shaving should be started on the right side of the head Sahih Muslim 1305 c
Arabic hadith text
وَحَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا عَبْدُ الأَعْلَى، حَدَّثَنَا هِشَامٌ، عَنْ مُحَمَّدٍ، عَنْ أَنَسِ، بْنِ مَالِكٍ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلمرَمَى جَمْرَةَ الْعَقَبَةِ ثُمَّ انْصَرَفَ إِلَى الْبُدْنِ فَنَحَرَهَا وَالْحَجَّامُ جَالِسٌ وَقَالَ بِيَدِهِ عَنْ رَأْسِهِ فَحَلَقَ شِقَّهُ الأَيْمَنَ فَقَسَمَهُ فِيمَنْ يَلِيهِ ثُمَّ قَالَ " احْلِقِ الشِّقَّ الآخَرَ " . فَقَالَ " أَيْنَ أَبُو طَلْحَةَ " . فَأَعْطَاهُ إِيَّاهُ
Translation
Anas b. Malik (Allah be pleased with him) reported that Allah's Messenger (ﷺ) threw stones at Jamrat al-'Aqaba. He then want to his sacrificial animal and sacrificed it, and there was sitting the barber, and he pointed with his hand towards his head, and he shaved the right half of it, and he (the Holy Prophet) distributed them (the hair) among those who were near him. And he again said
Shave the other half, and said: Where is Abu Talha and gave it (the hair) to him.