@adi47 ,
2.1 -- generally it should be the date of adjustment or the date on which you entered after adjustment -- so if you were present in USA in both the day prior and the day of adjustment, then it is the day of adjustment. This you will see that on the paperwork for the adjustment
2.2 --- your conclusion is correct..
Note that , if you have had zero foreign income during all of 2021, then there is a case to be made for exercising the first year option and file as a Resident for Purposes for the whole year. you would be able to use standard deduction and all the credits etc. would be available for the year.
Is there more I can do for you ?
