Built and perfected
Rashi (Sukkah 41a) writes that the future Temple, "built and perfected, will be revealed and come from Heaven."
The morning of redemption
The Or HaChaim (Leviticus 6:2) teaches that six thousand years parallel the six days of creation, the sixth millennium being Erev Shabbat. This is shared as hope, not a timetable.
What is in our hands
Learning Torah, love for one another and keeping mitzvot are how we become worthy of redemption.
Sources
Third Temple · Beit HaMikdash · Or HaChaim