There is nothing wrong with going to ‘Arafah on the night before the ninth of Dhu’l-Hijjah for fear of the crowds
Question

                I went for Hajj with a group and we stayed in Mina during the night before the ninth of Dhu’l-Hijjah, and we left it to head towards ‘Arafah before Fajr prayer, and we prayed Fajr in ‘Arafah, because the people in charge of the group did this for fear of the crowds. Do we have to do anything?.
Praise be to Allah.You do not have to do anything, but it is better for the pilgrim to go to ‘Arafah from Mina after sunrise on the ninth day of Dhu’l-Hijjah. 
And Allaah is the Source of strength. May Allaah send blessings and peace upon our Prophet Muhammad and his family and companions. End quote. 
Standing Committee for Academic Research and Issuing Fatwas 
Shaykh ‘Abd al-‘Azeez ibn ‘Abd-Allaah ibn Baaz, Shaykh ‘Abd al-Razzaaq ‘Afeefi, Shaykh ‘Abd-Allaah ibn Ghadyaan, Shaykh ‘Abd-Allaah ibn Qa’ood. 
Fataawa al-Lajnah al-Daa’imah li’l-Buhooth al-‘Ilmiyyah wa’l-Ifta (11/210, 211).