extracting data from lines in a log file

[hondahawkrider]

Having a little difficulty...and was hoping to be pointed in the right direction
I have a huge amdas log file with lots of data - several thousand rows
I am looking to parse two lines so i could do a comparison between the timestamp
The beginning line is
INFO : 2020-11-06 13:58:54.814: (thread: 1333782272): ==> Received payload from Postfix
The ending line is
INFO : 2020-11-06 13:58:55.449: (thread: 1333782272): ==> TRANSACTION completed.

There are several lines in-between and several instances per file - the unique values are "Received payload from Postfix" and "TRANSACTION completed" …
Where I am attempting to get the Received time stamp into column A and completed time stamp to column B..
I can import the file, not problem but having issues with the values, and help is appreciated... My macro skill are rusty..

 

[Yongle]

TimeStamp is calculated and retained as "Double" to maintain accuracy
Format the cells in your worksheet to show as date

To test ...
... Insert these CallFunc and GetTimeStamp in the same module and run CallFunc

Sub CallFunc()
    Const Alpha = "INFO : 2020-11-06 13:58:54.814: (thread: 1333782272): ==> Received payload from Postfix"
    Const Omega = "INFO : 2020-11-06 13:58:55.449: (thread: 1333782272): ==> TRANSACTION completed."
    Range("A1") = GetTimeStamp(Alpha)
    Range("B1") = GetTimeStamp(Omega)
End Sub

Private Function GetTimeStamp(LineOfText As Variant) As Double
    Dim d, t
    d = Split(Split(LineOfText)(2), "-")
    d = DateSerial(d(0), d(1), d(2))
    t = Split(Split(LineOfText)(3), ":")
    t = (t(0) * 60 * 60 + t(1) * 60 + t(2)) / 86400
    GetTimeStamp = d + t
End Function

Importing first and last line
You said that you have already imported the 2 lines so you do not need code below
This is probably a different method to extract first and last line from a textfile

Sub ReadTextFile()
    Dim a As Long, myFile As String, TextLine As String, Alpha, Omega
    myFile = "C:\test\Folder\subfolder\FileXXX.txt"
    Open myFile For Input As #1
    Do Until EOF(1)
        Line Input #1, TextLine
        If a = 0 Then Alpha = TextLine
        Omega = TextLine
        a = 1
    Loop
    Close #1
    MsgBox GetTimeStamp(Alpha) & vbCr & GetTimeStamp(Omega)
End Sub