Jamieson, Fausset and Brown on Zechariah 1:7

7. The general plan of the nine following visions (Zec 1:8-6:15) is first to present the symbol; then, on a question being put, to subjoin the interpretation. Though the visions are distinct, they form one grand whole, presented in one night to the prophet's mind, two or three months after the prophet's first commission (Zec 1:1).

Sebat--the eleventh month of the Jewish year, from the new moon in February to the new moon in March. The term is Chaldee, meaning a "shoot," namely, the month when trees begin to shoot or bud.