I’ve heard that the foreign opposition to the reconstruction of Jerusalem and the Temple were allowed to temporarily succeed in stopping the holy work because the Prophet Jeremiah’s 70 year sentence wasn’t fulfilled concerning the "time" Jerusalem had to serve as punishment for their sins. After that time appear the Prophets Haggai and Zechariah and basically say, "Get back to work. G-d is with you political and religious leaders of Judah!" WHY would G-d let the work begin so wonderfully and apparently bless their efforts, only to permit it to be forcefully stopped? Why discourage Zerubbabel and the "Temple Mount Faithful" of their day by not letting the momentum build until the Work was done? If it wasn’t the anointed and appointed time, why not say, "Just wait 15 years boys and have I got a job for you?"

You are probably referring to the Radak's explanation at the beginning of Sefer Haggai. Radak writes that the construction of the second temple began fifty-two years after the destruction of the first, seventy years after the rise of Nebuchadnezzer. This did not succeed, continues the Radak, because since the time for rebuilding the temple had not come- the work was not Divinely inspired and was therefore lackluster and lazy, easily discouraged by outside obstacles others set in its path. When the time to build the Temple arrived, Zerubavel was informed by the prophets that the lack of enthusiam that had previously plagued the construction would give way to Divinely inspired labor.