VBA - Insert a IF function within an exiting coding.

Hello All,
I need to insert a piece of coding in an existing code and I am totally new to VBA. here is the original code :

Public Sub ActualServiceLevelAchieved()
    Dim rngActualRequestDate As Range
    Dim rngRequestDate As Range
    Dim dtmDelivery As Date
    Dim dtmRequestDate As Date
    Dim lngSLA As Long
    For Each rngActualRequestDate In Sheets("DATA").Range(Sheets("DATA").Range("A2"), _
        Sheets("DATA").Range("A1048576").End(xlUp))
        lngSLA = Intersect(rngActualRequestDate.EntireRow, Range("B1").EntireColumn)
        If Len(rngActualRequestDate) > 0 And lngSLA > 0 Then
            dtmDelivery = rngActualRequestDate
            dtmDelivery = AddBusinessDay(dtmDelivery, lngSLA, Intersect(rngActualRequestDate.EntireRow, Sheets("DATA").Range("State").EntireColumn))
            dtmRequestDate = Intersect(rngActualRequestDate.EntireRow, Range("R1").EntireColumn)
            'If weekend or weekday > 3pm.
                If Weekday(dtmRequestDate, vbMonday) >= 6 Or CDbl(TimeValue(dtmRequestDate)) >= 0.625 Then
                    Else: dtmDelivery = CStr(Format(dtmDelivery, "d/mm/yyyy")) & " 17:00"
                End If
            'Populate date.
            Intersect(rngActualRequestDate.EntireRow, Sheets("DATA").Range("ActualServiceLevelAchieved").EntireColumn) = dtmDelivery
        End If
    Next rngActualRequestDate
End Sub

What I want to do is to add a condition in the section : 'If weekend or weekday > 3pm.
I have a new column (column O) with 4 types of values possible : FULL, RESTRICTED, DESKTOP and RURAL.
what if want to do is : IF the value in Column O is FULL, RESTRICTED or RURAL then the part of the code :

'If weekend or weekday > 3pm.
                If Weekday(dtmRequestDate, vbMonday) >= 6 Or CDbl(TimeValue(dtmRequestDate)) >= 0.625 Then
                    Else: dtmDelivery = CStr(Format(dtmDelivery, "d/mm/yyyy")) & " 17:00"
                End If

Is to be applied. If the cell in column O is = DESKTOP, then this coding is not to be applied.

I don't know if it makes sense to you or not. Please let me know if you you need more info.

Thanks.