Also I don't know which language you are using, however you can change the language for the user like:

Check the language that has the first date Monday... more correct check the value of the DateFirs col, that is third col in your results. is it 1!

SELECT * FROM sys.syslanguages

Then, now try to change the language of the user that you've created to run schedule jobs, like this:

USE [master]

GO

ALTER LOGIN WITH DEFAULT_LANGUAGE = "Your language that you have choose to be from syslanguages"

GO

Sample:

USE [master]

GO

ALTER LOGIN [YourUserName] WITH DEFAULT_LANGUAGE = [Deutsch]

GO