This is a good opportunity to practice being not so codependent. Do it when it's convenient for you. Don't go out of your way for her sake. You might feel anxiety about doing that, but that's okay. It'll get easier over time.

If you can do it today and feel motivated, do it. If you are busy and can't get it done until next week, then she's just going to have to live with that. She's a grown up, she can start acting like it, including accepting consequences of her actions and inactions. It's not like you haven't given her the chance.

Don't postpone out of spite though- that will only bother you and make her more of a victim.