So far, there isn't any official way of doing that and when I say official, I mean AWS authorized or recognized.
But there is a way you can get your user data status. What you need to do is, have your user data script add an additional label to the instance after it completed. Then you can do a describe-instances with a filter that will only include the nodes with the tag you use to specify that the user data has been updated.
This method will also require you to include an API key and secret in your user data script. Do not include your regular API key and secret. You can create one with very limited IAM rights and use that one.