Hello,
You should :
1. Create a job which runs yous SSIS package with no schedule (JOB 1)
2. Create a stored procedure (SP_MyStoredProc) which calculates your interval and verify if you are in the working day and day number and run JOB 1 if the condition is respected
3. Create JOB 2 with "once per day" schedule interval which has one step - run your SP_MyStoredProc
That's all
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