CREATE TABLE table_71979 ("Location" TEXT, "Year" FLOAT, "Champion" TEXT, "Runner-up" TEXT, "Score" TEXT)

When is the earliest year in milan that guillermo vilas was champion?
SELECT MIN("Year") FROM table_71979 WHERE "Location" = 'milan' AND "Champion" = 'guillermo vilas'
SELECT MIN("Year") FROM "table_71979" WHERE "Champion" = 'guillermo vilas' AND "Location" = 'milan'