user: Question: When did Gaspare Bona win the Pozzo Circuit?
Columns: ['Name', 'Circuit', 'Date', 'Winning driver', 'Winning constructor', 'Report']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Tripoli Grand Prix', 'Tripoli', '6 March', 'Emilio Materassi', 'Bugatti', 'Report']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Winning driver" = 'Gaspare Bona' AND "Name" = 'Pozzo Circuit';