Having looked through the rules, I certainly find this an intriguing idea.
I'm wondering if some of you more crunch-oriented power-gamer types can provide some insight as to when having your PC's 'ascend' to mythic is most ideal. It seems to me that they could receive the mythic bump (patent pending) at just about any time, but I'm not particularly gifted at the analysis necessary to confirm this.
Were I to, say, in a carrion crown campaign give the mythic bump(patent still pending) after say, the climax of book three, would it be more ideal and more noteworthy to the pcs at roughly lvl 9 tier 1, than if I awarded it at the climax of the entire adventure path, at roughly lvl 17, tier 1?
Thanks.
There's obviously no need to give all mythic tiers, any more than there's a need to get to level 20 to call a campaign completed.
The best approach is to pick a story-appropriate moment (I can't help with that in Carrion Crown as I haven't gotten around to reading through it), and give them one or more mythic tiers at that point. Then, unless you want to make the campaign easier than intended, reduce their XP gain and hold off on giving them levels, so that the party's Level + Tier remains equal to the level listed for that part of the AP.
Holding off until the very end is just not going to give the party much opportunity to enjoy their powers... at least in the AP. If you're planning to do continue the campaign after the AP ends, that may work out, though.