Calculating an interval of time

Private Enum MSeconds
        Days = 86400000
        Hours = 3600000
        Minutes = 60000
        Seconds = 1000
End Enum
 
Private Function GetNextInterval() As Long
        Dim day As Integer = Now.DayOfWeek
        Dim day2 As Integer = DayBox.SelectedIndex
        Dim d As Integer = 0
        Dim h As Integer = CInt(Split(TimeBox.Text, ":")(0))
        Dim m As Integer = CInt(Split(TimeBox.Text, ":")(1))
        Dim s As Integer = 0
        ' number of days til next backup
        If day > day2 Then
            ' if today is past backup day
            d = 7 - (day - day2)
        ElseIf day2 > day Then
            d = day2 - day
        Else
            'day=day2
            Dim time As New Date(Now.Year, Now.Month, Now.Day, h, m, s)
            Dim ts As TimeSpan = time - Now
            If ts.TotalMilliseconds > 0 Then
                ' its passed already
                d = 6
            Else
                d = 0
            End If
        End If
 
        ' number of hours
        If h = 0 Then
            ' use 24
            If Now.Hour = 0 Then
                h = 0
            Else
                h = 24 - Now.Hour
            End If
        Else
            If h > Now.Hour Then
                h = h - Now.Hour
            ElseIf h < Now.Hour Then
                h = 24 - (Now.Hour - h)
            Else
                h = 0
            End If
        End If
        ' number of minutes
        If m = 0 Then
            ' use 60
            If m = Now.Minute Then
                m = 0
            Else
                m = 60 - m
            End If
        ElseIf m = 30 Then
            If m > Now.Minute Then
                m = 30 - Now.Minute
            Else
                m = 60 - (Now.Minute - m)
            End If
        End If
        ' number of secods - leave at 0
        s = 0
        Return d * MSeconds.Days + h * MSeconds.Hours + m * MSeconds.Minutes + s * MSeconds.Seconds
    End Function