I think the first option you propose is better than the 2nd.

 - In the 2nd, the user will be **out of her workflow**, and ask for maybe a 3 days or even weeks old action is not a good idea imo: it would be **frustrating** for the user because she won't be able to do immediately what she aimed to do when using your app.
 
 - In the 1st option, that's **much better** the way you thought it could be in the user flow: after everything completed, and hopefully an amazing experience through your product, the user is much more ready to be kind and give you feedback.
It should not stop the user in her flow; I mean, you can probably add a call to action to invite the user answer your questions, but the modal or pop up might not be the best solution. It creates frustration and it's called ***modal excise***, which is right in front the user without her consent, and she can not do anything else until she deals with the modal (one action to do too many)

Hope I helped you ✌️