What's the meaning of "his day"?

Question

From NPR: 'Made For This': The Rootless Life Of A Roving Musician

This passage describes David Dondero: a singer, songwriter as well as a transient. The following text is just a quotation about how Bazan recognized Dondero and his impression of Dondero.

MASTERS: Bazan says he admires his friend. He first met him when they toured Europe in 2008. Bazan says he watched him every night.

BAZAN: Whoever's in the room, even if they don't know about him prior, are just kind of captivated and it energizes him. And I could see it over and over again; him being plagued with self-doubt, you know, when he's not on the stage, when he's kind of going about his day. And then he gets up on stage and it's a reminder to him, like, oh yeah, I'm kind of made for this.

I have two questions:

1. It seems that the word prior stressed above is used as an adverb. But from the dictionary, prior can only be used as adjective and noun. So is it wrong in the passage?
2. What's the meaning of his day in the quotation?

Answer 1

Here prior is being used as a shorthand of sorts for a fuller phrase such as "prior to meeting him here" or "prior to coming into the room". It is technically not correct usage, but it is probably relatively common in some areas. (Since I don't know where "Bazan", the speaker, is from, other than 'not from my area', I can't really say how common it might be; but it's not common in my area, at least.)

"Going about his day", as noted in the comments, is an idiom meaning to do all the normal, run-of-the-mill, routine things that you usually do every day; shower & shave, eat breakfast, read the papers, check your e-mail, get ready for work, and so forth.