DateTime manipulation..Need help

[Puru]

I need some help in generating Invoice Number in my Program using current System Date. I have made the following declarations as given below.

Dim d1 As DateTime = DateTime.Now
Dim MyDate As String = d1.ToString("yyMMdd")

Since the Date changes at Midnight which ultimately reflects in the next Invoice number. I want to keep the previous Date in invoice number till the System time reaches 12:00 noon.

i.e
If (d1.Hour < 12) And (d1.Hour > 0) Then
......(Here in need the required code to retain the Previous System Date)
.....
End If

Please guide me!!

 

[PLH]

I am not sure if I understand your question.
<I want to keep the previous Date in invoice number till the System time reaches 12:00 noon. >

If you'll be more clear I may help you.