Pass the dates as parameters to the procedure:
CREATE Proc [dbo].[DawgAlert_Completed_Order_Status] (@LoadDate datetime, @EndDate datetime, @billto varchar(100))
You may call the procedure with parameters:
exec [dbo].[DawgAlert_Completed_Order_Status] '2019/01/01','2019/01/02','bill to address'
For more info:
https://docs.microsoft.com/en-us/sql/relational-databases/stored-procedures/create-a-stored-procedure?view=sql-server-ver15