SELECT "Date" FROM table_4350 WHERE "Competition" = 'friendly' AND "Score" = '2–1' AND "Venue" = 'philadelphia , pennsylvania'
When did a Competition of friendly, and a Score of 2 1, and a Venue of philadelphia , pennsylvania occur?
CREATE TABLE table_4350 (
    "Date" text,
    "Venue" text,
    "Score" text,
    "Result" text,
    "Competition" text
)