Per article from Khaleej Times dated 8th October 2017:
All businesses with a turnover exceeding AED 150m should apply for VAT registration before 31st October 2017.
All businesses with a turnover exceeding AED 10m should apply for VAT registration before 30th November 2017.
All businesses that must be registered by 1st January 2018 should submit their VAT registration applications before 4th December 2017 to minimize the risk of not being registered in time for the beginning of the new year.