The festive month of Cheshvan

Our Sages state that the construction of the First Beis Hamikdash was completed in the month of Marcheshvan but its inauguration was postponed (by Heaven) for twelve months; it was inaugurated in the following Tishrei and the month Marcheshvan ‘lost’ its only chance of hosting a festive occasion. Therefore, Hashem will in the future ‘repay’ Marcheshvan by inaugurating the Third Hamikdash then. (Parshas Bereishis 5750; Hisvaaduyos p.294-6.)

Beis Hamikdash now, celebration in Cheshvan

Not that we will have to wait until the month of Marcheshvan [if the Third Mikdash arrives earlier] ... but rather the Redemption will occur immediately and the Mikdash will obviously be ready and standing when Marcheshvan arrives. (ibid, footnote 22)