The nine months could actually be more than ten months. See, the first 3.5 years will end on 24 Elul 5775, being the end of 1335 days, 1335-1290 days after Tisha B'Av. From there, count 7 years and 3 months.
That brings us to 24 Kislev 5783, the day before Chanukka. From this day, the 24th day, I will bless you. On that day, I will shake the heavens and the earth (Chaggai).
And the reason for waiting so long, is the Torah of the priests, as explained (here and Chaggai 2:11-15).
