Q. If the chosson will not be davening mincha with a minyan can he say the viduy in maariv?

A. Piskei Teshuvo (E. H. 65: 14) quotes the opinion of the Sh’loh and others that it is tradition to recite viduy (similar to Yom Kippur) on Mincha even in the days when no tachanun is said.

When the chupa will take place before mincha, Poiskim rule that viduy should be recited in the shacharis tefilah. If then the chupa was delayed and they were able to daven mincha before, viduy should be recited again (Shulchan Hoezer 2: 17, Nitey Gavriel – H. Nisuin 1: 8: 9).

Horav Shlomo Miller’s Shlit”a opinion is that the viduy should be recited during mincha of the day of their fasting and atonement, not during the maariv after.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a