Let's see here.
I'd be surprised if Easter Egg ends up being something that would require a lot of time to mix, same with the intro track. A bit of an assumption on my part there, but I just don't see either of those being complex songs, if songs at all. I'd maybe even put those at a day or two for the pair.
I'd also expect the usual variety of track lengths, at least a couple of "single" length, which would also take less time to mix, maybe a day each.
Then the remaining tracks would probably be 2-3 days each.
"Best part of a month" is a great bet as far as vague definitions of timespans go.