Idioms – Meaning of ‘Call it a Day’

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.

In most contexts, in the first place [assertion A] is a somewhat metaphoric usage where first doesn't really have anything to do with the temporal sense of A being in some way earliest in time.

It's usually used in contexts where there are several relevant factors that might be mentioned by the speaker. But assertion A is the most important one (and/or the one from which further supporting assertions logically follow, and the speaker intends to go on and make those further assertions).

In short, it's sense 2 in oxforddictionaries: first - Foremost in position, rank, or importance.

USAGE NOTE: The metaphorical usage referred to above almost always occurs before the relevant assertion. Consider...

1: In the first place John was there.
(The fact that John was there is central to the points I'm about to make.)

2: John was there in the first place.
(John was already there before whatever happened next that I'm going to tell you about.)

It's also worth noting that usage #1 generally occurs in contexts where the speaker is refuting, or disagreeing with someone else's prior assertion (you wouldn't be so likely to use it as the opening line to start a conversation or make a point).