So what you really want, is the last value greater than current one. The max previous value can be somewhere before Jan 11.
Another thing is, you are speaking about dates, but you are checking row-wise. What is 'previous' for you - the previous date, or previous row. What happens when the table is rearranged (sorted) by some other column. In case you check not date-wise, but row-wise, your formula's results most probably will be entirely different.