Indeed, it was interesting reading. Thanks. Still stuck though. Here is the
code and below I'll tell you what I tried:
Private Sub cmdBuildSchedule_Click()
   Dim datThis As Date
   Dim lngActID As Long
   Dim lngLocID As Long
   Dim varNotes As Variant
   Dim strSQL As String
   Dim db As DAO.Database
   Dim intDOW As Integer 'day of week
   Dim intDIM As Integer 'Day in month
   If Me.grpRepeats = 2 Then
       If Not CheckDates() Then
           Exit Sub
       End If
   End If
   If Not CheckTimes() Then
       Exit Sub
   End If
   If IsNull(Me.cboActID) Then
       MsgBox "You must select an Activity.", vbOKOnly + vbInformation,
"Enter Activity"
       Me.cboActID.SetFocus
       Me.cboActID.Dropdown
       Exit Sub
   End If
   If IsNull(Me.cboLocID) Then
       MsgBox "You must select a Location.", vbOKOnly + vbInformation,
"Enter Location"
       Me.cboLocID.SetFocus
       Me.cboLocID.Dropdown
       Exit Sub
   End If
   'strTitle = Me.txtTitle
   varNotes = Me.txtNotes
   lngLocID = Me.cboLocID
   lngActID = Me.cboActID
   Set db = CurrentDb
   If Me.grpRepeats = 2 Then 'need to loop through dates
       For datThis = Me.txtStartDate To Me.txtEndDate
           intDIM = GetDIM(datThis)
           intDOW = Weekday(datThis)
           If Me("chkDay" & intDIM & intDOW) = True Or _
                   Me("chkDay0" & intDOW) = True Then
               strSQL = "INSERT INTO tblTempSchedDates (" & _
                   "tscDate, tscActID, tscLocID, " & _
                   "tscStartTime, tscEndTime,  tscNotes ) " & _
                   "Values(#" & datThis & "#," & lngActID & ", " & _
                   lngLocID & ", #" & Me.txtStartTime & "#, #" & _
                   Me.txtEndTime & "#," & _
                   IIf(IsNull(varNotes), "Null", """" & varNotes & """") &
")"
               db.Execute strSQL, dbFailOnError
           End If
       Next
    Else  'dates are there, just add the title, notes, times, location,
Activity
       strSQL = "Update tblTempSchedDates Set tscActID = " & lngActID & _
           ", tscLocID = " & lngLocID & ", tscStartTime =#" &
Me.txtStartTime & _
           "#, tscEndTime = #" & Me.txtEndTime & "#"
           
       If Len(varNotes & "") > 0 Then
           strSQL = strSQL & ", tscNotes = " & IIf(IsNull(varNotes), Null,
"""" & varNotes & """")
       End If
       db.Execute strSQL, dbFailOnError
   End If
   Me.sfrmTempScheduleEdit.Requery
   MsgBox "Temporary schedule built. " & _
       "You can now edit the schedule and " & _
       "append to the permanent schedule.", vbOKOnly + vbInformation, "Temp
schedule complete"
End Sub

OK. Since the date is taken from datThis, I tried:

For datThis = Format(Me.txtStartDate, "mm\/dd\/yyyy") To
Format(Me.txtEndDate, "mm\/dd\/yyyy")

That didn't work so in the strSQL I tried:

strSQL = "INSERT INTO tblTempSchedDates (" & _
                   "tscDate, tscActID, tscLocID, " & _
                   "tscStartTime, tscEndTime,  tscNotes ) " & _
                   "Values(#" & Format(datThis, "mm\/dd\/yyyy") & "#," &
lngActID & ", " & _
                   lngLocID & ", #" & Me.txtStartTime & "#, #" & _
                   Me.txtEndTime & "#," & _

Unfortunately, that didn't work either. I wondered if the wrapping function
would be the best way to go, but had even less ideas on how or where to put
that.  The form controls are unbound. I set the formats in the date fields to
'Short Date'

Thanks again
Ana