There is a big discrepancy to take note of here. It is the difference between Databricks job costs (DBUs) and billing for the cloud provider (the actual VM doing the the work). 

Billing for the Databricks job starts when the Spark context is being initiated (you can see so in the event log). It is usually at 4-5 minutes in. 
Billing for the cloud provider starts the moment you press the start button on your pipeline (this will provision the VM in 5 minutes). 

Hope this helps!