In February 2012, Harold took the silver medal at the French Indoor Championships at Aubière, and later that year won his first national title at the French Outdoor Championships in Angers. In 2013 he became France’s indoor champion with a 16.94 m jump--beating his personal record by 11 cm. His performance also qualified him for the European Indoor Championships in Gothenburg, Sweden, where he took 5^th place.

On 24 July 2015, a few days after his second French championship title, Harold joined the SNCF Athletes Programme as a customer care agent at Paris Lyon station. The programme gave him the support he needed to keep improving, and in 2016, at a meet in Montgeron, near Paris, he broke the 17 m barrier.

Later that year he won the Interclub final in Villeneuve-d’Ascq, with a 17.08 m jump that qualified him for the Olympic Games in Rio and the European Championships in Amsterdam.