How long did it take after patient number 821298 arrived at the hospital for the first time before her evaluation began?
DATEDIFF(`Examination Date`, `First Date`)
SELECT STRFTIME('%d', T3.`Examination Date`) - STRFTIME('%d', T1.`First Date`) FROM Patient AS T1 INNER JOIN Examination AS T3 ON T1.ID = T3.ID WHERE T1.ID = 821298