Lewis & Short

ecquando, adv. interrog. [ec, cf. ecce, and quando], ever, at any time; in a passionate (esp. indignant) interrogation (rare but class.): ecquando te rationem factorum tuorum redditurum putasti? ecquando his de rebus tales viros audituros existimasti? Cic. Verr. 2, 2, 17; 2, 5, 26; Cael. ap. Cic. Fam. 8, 15; Liv. 3, 67; Sen. de Ira, 3, 28; Val. Fl. 2, 395.
With nisi (= num unquam … nisi), Cic. Fin. 5, 22, 63; id. Agr. 2, 7, 17.

        1. (β) With interrog particle ne suffixed (pleonastic): ecquandone tibi liber sum visus? Prop. 2, 8, 15; Vell. 2, 14, 2 Ruhnk.; App. Mag. p. 290.
          With nisi, Cic. Fin. 5, 22, 63 Madv. N. cr.