What is yours current repertoire? We cannot say to you when is right time to try ballade; you should know it. But, surely, all these concertos are not required.
Uhm. My repertoire basically is:
Bach: all 2 and 3 parts inventions, some pieces from french suites, partita 1. Some PF WTC I and II. Concerto in G minor
Mozart: Rondò in D, Sonatas 545, 331, 283. Concert 19 F major
Beethoven: Paisiello variations, Sonatas op. 49 1/2 op. 13 op. 6/3
Mendelssohn: Some Songs without Words, Rondó Capriccioso, Scherzo in E minor
Scarlatti: some sonatas
Chopin: Preludes 3, 4, 6, 7, 15, 20, 21, 22
Mazurkas 22-25
Waltzes: 3, 10, posthomous in A minor
Rachmaninov: Preludes 3/2, 23/5, 3 nocturnes
Schumann: Kinderszenen, Waldszenen, Papillons.
Grieg: some lyric pieces, Holberg Suite (complete)
I don't know if it's enough, or if I am intermediate or early advanced.