I say, and with Allah's guidance: There is no zakat on one who possesses the nisab unless a complete lunar year has passed since the day the wealth reached the nisab. See: Red al-Muhtar (2: 8), Al-Bahr al-Ra'iq (2: 222), Fath Bab al-'Inaya bi Sharh al-Niqaya (1: 505), and Tabyin al-Haqaiq (1: 253), and Allah knows best.