CREATE TABLE table_40540 ("Date" TEXT, "Cover model" TEXT, "Centerfold model" TEXT, "Interview subject" TEXT, "20 Questions" TEXT)

When has a Centerfold model of pilar lastra?
SELECT "Date" FROM table_40540 WHERE "Centerfold model" = 'pilar lastra'
SELECT "Date" FROM "table_40540" WHERE "Centerfold model" = 'pilar lastra'