Rabbi

And since it completes the Nisuin, according to the Rambam and the Mechaber, she would then need to cover her hair if they had Yichud.

And most Kalas don't want to cover their hair at the wedding.

So she would need to put on a sheitel right away.

she would need to put on a tichel or something right away at the yichud, and most women do not want to be covering their hair at their wedding, so they wait until after the wedding to complete the marriage, so that they won't have to cover their hair until afterwards.

Rabbi Willig often points out that really full hair covering is only required

after Bia Rishonah.

It's not Nisuan, that's the Mechayev of hair covering.

There's a major Machlogsha Poskan.

There are Poskan that hold that from Aresin and on, you already need full hair covering, and therefore a Kala's got to even go to the Chuppah, march down the aisle with a full hair covering.

There are those that suggest...

that it's only at Nisuin, and then Rav Willick suggests, and many others, that it's only from the B'yari Shona, because the chiv to cover a hair is derived from the Pesukim Parshas Nasa, that is Sotah, and a woman cannot become a Sotah until B'yas Mitzvah, so perhaps the covering of the hair, the obligation begins at the B'yas Mitzvah.

So the only requirement at the wedding itself to have any sort of hair covering at the wedding itself is based on the description that the Mishnayis have in Masechas K'subas of a color that's Yotze B'Hinumah, that there's something...

There's some sort of head covering that's indicative of being a kala.

So that's why Rav Shachter recommends to kalas that they should wear their veil throughout the wedding, not over their face, but on their head, that the veil should be there, that there should be some form of head covering

There are different, you know, every kala tries to negotiate this down, right?

Meaning, what if it's just a headband?

What if a barrette?

What if, you know, there's a piece of dirt somewhere in my hair?

You know, so some hairspray, is that good?

So, but nevertheless, there should be some sort of head covering, but not because of the normal din of head covering, but because of this din, this idea of Yotzi being Numa.