Wpf datagrid adding new row setting focus first cell

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WPF

DataGrid

WPF DataGrid while adding new row focus is always setting to last position of cell.
How would I can set to the first cell's focus while adding new row?

1.I have simple 6 columns so when I press enter on last column it should add new row (working fine)
2.Focus should be the added row's first cell it won't happen it is always in the last cell

I am attaching my WPF Sample demo as well please correct me where I am wrong? Demo Link: WPFDemo

https://github.com/jitendrajadav/WPFDEMO

Thank you,
Jitendra Jadav.

What I have tried:

I have tried with 3 days of google and MSDN but couldn't find any solution for it.