Direct damage and planeswalkers

[Valtrix]

So, I know that if a player deals direct damage, with say a lightning bolt that you target a player and then if they have a planeswalker you can choose to redirect that damage. What I'm concerned about is when the redirect effect is declared. From checking the rules, I feel like the redirect happens as the lightning bolt is resolving, not when the bolt is cast (because the target is a player). Is this the case?

Then, if the above is correct, if my opponent casts lightning bolt targeting me and I have a Jace in play and ask "Me or Jace?" am I agreeing that the lightning bolt resolves and would be unable to counter it anymore?

[ween]

They are presented with the choice to redirect damage as part of the resolution, not at the time of choosing a target. The Planeswalker itself isn't being targeted with the spell.

In your example, you're past the point of being able to counter the spell if you're asking if they wish to redirect the damage.

[Valtrix]

That's what I suspected, although I wanted to be sure.