The Konzertstück in F minor for Piano and Orchestra, Op. 79, J. 282, was written by Carl Maria von Weber, and he started work on it in 1815, and completed it on the morning of the premiere of which opera, with spoken dialogue in three acts?
Konzertstück in F minor (Weber):  He started work on it in 1815, and completed it on the morning of the premiere of his opera "Der Freischütz", 18 June 1821. Der Freischütz: Der Freischütz , Op. 77, J. 277, (usually translated as "The Marksman" or "The Freeshooter") is a German opera with spoken dialogue in three acts by Carl Maria von Weber with a libretto by Friedrich Kind.
Der Freischütz