Amdouni made his junior international debut in the 1500 metres at the 2006 World Junior Championships in Athletics but did not progress past the heats. At the 2006 European Cross Country Championships he finished twelfth in the junior race, gaining the team bronze medal with France alongside Noureddine Smaïl. He made significant progress in the junior ranks the following year: first, he managed 38th place at the 2007 IAAF World Cross Country Championships and then he won the 5000 metres gold medal at the 2007 European Athletics Junior Championships. In the winter season, he went on to win the junior race at the 2007 European Cross Country Championships, leading the French juniors to victory along with runner-up Florian Carvalho.