VBA to show the first username that opens the book

[Joige]

I'm looking for a function that shows the windows username of the first person who opened the book.
Looking online I found two VBA that got me close to what I wanted, but I haven't managed to combine them since I understand close to nothing of VBA code.

I have a name "OpenFirstTime" set to TRUE and this code

Private Sub Workbook_Open()
    If Evaluate("OpenFirstTime") = True Then
        'missing code
        ThisWorkbook.Names("OpenFirstTime").Value = False
    End If
End Sub

I also have this function that shows the CURRENT windows username

Function UserName() As String
    UserName = Environ("USERNAME")
    
End Function

Again, I'm looking for a way to run the function on the first workbook open, save the result, and then, with another function, call that result.
Is that even possible?

Thanks!

 

[Logit]

Create a sheet named "Log". It can be hidden from user view if desired.

Paste the following into the 'ThisWorkbook' module in the VBE :

Private Sub Workbook_Open()
Dim LR As Long

    With Sheets("Log")
        LR = Range("A" & Rows.Count).End(xlUp).Row
        Range("A" & LR + 1).Value = "Opened"
        Range("B" & LR + 1).Value = Now
        Range("C" & LR + 1).Value = Environ("username")
    End With
    
End Sub

 

[Joige]

Create a sheet named "Log". It can be hidden from user view if desired.

Paste the following into the 'ThisWorkbook' module in the VBE :

Private Sub Workbook_Open()
Dim LR As Long

    With Sheets("Log")
        LR = Range("A" & Rows.Count).End(xlUp).Row
        Range("A" & LR + 1).Value = "Opened"
        Range("B" & LR + 1).Value = Now
        Range("C" & LR + 1).Value = Environ("username")
    End With
   
End Sub

Thanks for the reply, but that's not really what i'm looking for.
I would prefer not to add anything to the workbook, I'd like to have the current user function which returns the current user when called in a formula UserName(), and another that returns the first user that opened the work bookFirstUserName().

Example:
I open the workbook the first time and both function return "Jorge". I save it and send it to a friend. When he opens it UserName() returns "Joe" and FirstUserName() returns "Jorge"

Sorry but it's hard to explain myself with 0 knowledge on VBA. Thanks!

 

[Joige]

I don't know if this is even possible. If not, please let me know and I'll try to find another way to make this work.