So, if you use {id} it will be replaced by the max order_invoice_id + 1.
If you want the next order's number to be bigger than the current one, you can create an order and change its order_invoice_id to be one lower. For example, if you want the next order's number to start with 2000, you want to set 1999 in the order_invoice_id of your order via PHPMyAdmin.
If you want the next order's number to be lower than the current one, then it's a bit more difficult. You would need to change the order_invoice_id of all the existing orders to be lower than the order_invoice_id you want. It's possible with a MySQL query (or a mass action with an "update the values" action on the order_invoice_id column).