Peace be upon you. Yes, according to Sayyid Sistani and Sayyid Khamenei, it is permissible to change the start of the five-year cycle by advancing it to an earlier date. The individual would then pay the khums (religious tax) on the surplus profits based on this new date, which would subsequently become the start of their five-year cycle. For more details, you can refer to the official websites of Sayyid Sistani and Sayyid Khamenei.