You can also achieve this in a single Instance configuration using multiple node types, and the post provision workflow. A post provision workflow will only execute once all nodes within an instance have finished provisioning (and IP address information up to date).
Continue with the blueprint approach for now. One thing you should explore is all the automation variables available to you in a workflow using the approach discussed here: Listing variables in Morpheus
You will most likely find the data you need and the variable to use to access it. The ‘app’ variable may be of interest for example.