At least when I deal with this all the time used in Web Application is the time machine using this site, regardless of the time that this server.
But you may need to configure Global.asax.vb (or just Global.asax)
With the following line:
Public nfi2 As CultureInfo = CultureInfo.InvariantCulture
And when using the data, you can use the value of local culture machine.
example:
Date.ParseExact(TextBoxDate.Text.Trim(), "d/M/yyyy", nfi2)