Running SSIS jobs sequentially in T-SQL We are loading ETL data in two parts, first with an SSIS package and then stored procedure.

In the script below, Part2 stored procedure will run even before SSIS Part1 is complete. How do I get Part2 Stored procedure to run only After completion of Part1 SSIS?

Is there a way to conduct this in T-SQL? Should we use delay function and check every few minutes with SSIS dmv SSISDB.catalog.executions if package is complete? Is there another way?

Background:
We can place sproc in a control flow arrow after SSIS. However, our company does not want to conduct this. We are more of a script based company. Additionally trying to refrain from SQL agent jobs. Currently QA department needs a way to run items, without creating multiple jobs. We created jobs for parent level packages, however do not want to create unit jobs for our 500+ SSIS and sprocs.

--Part 1
EXEC [SSISDB].[catalog].[create_execution] 
               @package_name=N'Customer_StageTable_Part1_Insert.dtsx'
               , @project_name=N'Datawarehouse'
               , @folder_name=N'Datawarehousefolder'
               , @use32bitruntime=False
               , @reference_id= 2
               , @execution_id=@execution_id OUTPUT

select @execution_id

--Part 2
execute Customer_StageTable_Part2_Insert


https://www.sqlshack.com/execute-deployed-package-ssis-catalog-various-options/
I think that approach will just complicate your task. 

What I'm thinking is a validation in a table, when your package starts insert something and then when it's completed insert something else, and then your "part2" when executed will look to the table if it's over execute this other wise wait for 5 minutes and execute this same check again.