I believe when you create a new droplet through the API you get a droplet id. You can use this id to fetch the information from a box.
See: https://developers.digitalocean.com/documentation/v2/#create-a-new-droplet
After that you can retrieve the droplet information using the id you get before. It will probably give some error message if the droplet isn't ready or not created yet, so you can catch that error and wait a few more minutes
See: https://developers.digitalocean.com/documentation/v2/#retrieve-an-existing-droplet-by-id