Many pilgrims throw pebbles at the Jamarat on the 11th, 12th, or 13th before the sun has passed its zenith. This is certainly wrong. Their stoning is not valid. They must perform it after the sun has passed its zenith toward the west, because no act of worship is valid before its prescribed time.
Some Hajj group leaders are seen leaving Mina with the pilgrims after midnight on the 11th. They spend the remainder of the night in Makkah, return from Makkah after Zuhr the next day to throw the pebbles, and then go back to Makkah. Doing so is contrary to the practice of the Messenger of Allah, may Allah bless him and grant him peace. This should not be done unless one faces particular difficulty. Both the night and the day should be spent in Mina. If spending the night in Mina is considered obligatory, then spending the day there is certainly Sunnah; there is no doubt about this. The Messenger of Allah, may Allah bless him and grant him peace, spent both the day and the night in Mina.
Many pilgrims who are muta‘ajjil, meaning those who depart early, throw the next day’s pebbles together with those of the current day. This is not correct at all, because it is also being done before its prescribed time, which is not valid. Therefore, they must refrain from doing this.
Many people depart Mina early after throwing the pebbles on the 12th, but then spend the night in Makkah and return to Mina the next day, the 13th, to throw pebbles again. This is not correct. This act has no validity.