Messenger of Allah ﷺ slaughtered (the Hadi) before he had his head shaved and then he ordered his Companions to do the same.  

أَنَّ رَسُولَ اللَّهِ ﷺ نَحَرَ قَبْلَ أَنْ يَحْلِقَ وَأَمَرَ أَصْحَابَهُ بِذَلِكَ  

That ʿAbdullah and Salim said to ʿAbdullah bin ʿUmar, "(You should not go for Hajj this year)." ʿAbdullah bin ʿUmar replied, "We set out with the Prophet (to Mecca for performing ʿUmra) and the infidels of Quraish prevented us from reaching the Kaʿba. Messenger of Allah ﷺ slaughtered his Budn (camels for sacrifice) and got his head shaved."  

خَرَجْنَا مَعَ النَّبِيِّ ﷺ مُعْتَمِرِينَ فَحَالَ كُفَّارُ قُرَيْشٍ دُونَ الْبَيْتِ فَنَحَرَ رَسُولُ اللَّهِ ﷺ بُدْنَهُ وَحَلَقَ رَأْسَهُ