user: Question: What is the lowest week that has 7:15 p.m. as the time (cst) and FedExField as the game site?
Columns: ['Week', 'Date', 'Time (CST)', 'Opponent', 'Result', 'Game site', 'Record', 'NFL Recap']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'September 7, 2008', '3:15 p.m.', 'at Cleveland Browns', 'W, 28–10', 'Cleveland Browns Stadium', '1–0', 'Recap']
SQL:

assistant: SELECT MIN("Week") FROM "Table" WHERE "Time (CST)" = '7:15 p.m.' AND "Game site" = 'FedExField';