Need a way to create invoice numbers automatically

[Thriftlife]

Hey needing a way for my company to use the invoice we have created and create a bunch of copies of it and give it its own unique invoice number.
The cell the invoice number will be in is I4
i would like it to save each copy as the same name as the invoice number, if thats possible. Or at least save each file without going in and manually saving each one.
We usually make 1300 or more copies of invoices that employees fill out, so trying to make it easier on us
,Thamks

 

[Thriftlife]

I got this far, go it to change the number when its open and to saveas invoice number it was changed to.
Anyone know how to get it to make it does this without me opening each file?

Private Sub Workbook_Open()
Range("I4").Value = Range("I4").Value + 1
End Sub

Sub SaveAsA1()
ThisFile = Range("I4").Value
ActiveWorkbook.SaveAs Filename:=ThisFile
End Sub

 

[Thriftlife]

Need to copy a file and rename it from a list i have created

 

[Thriftlife]

Sub SaveMasterAs()
Dim wb As Workbook
Dim rNames As Range, c As Range, r As Range

'Current file's list of names and ids on sheet1.
Set rNames = Worksheets("Sheet1").Range("A2", Worksheets("Sheet1").Range("A2").End(xlDown))
'Path and name to master workbook to open for copy, saveas.
Set wb = Workbooks.Open(ThisWorkbook.Path & "\Invoice Numbers.xlsm")

For Each c In rNames
With wb
.Worksheets("Sheet1").Range("A2").Value = c.Offset(, 1).Value 'ID
'Path and name for copied workbook
.SaveAs Filename:=ThisWorkbook.Path & "\2021" & c.Value & ".xlsm", _
FileFormat:=xlOpenXMLWorkbook, CreateBackup:=False
End With
Set wb = ActiveWorkbook
Next c
wb.Close
End Sub

Cant get this to work can someone help with it

 

[Thriftlife]

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