VS 2010 : Define IO.FileInfo Object As Private

In the following code as you see I am defining myFile inside the timer sub; which of course is not a good idea. The FilePath is derived in form load before the timer kicks in. How can I declare myFile globally so it can be used in timer sub as well as in form load?

Private Sub tmrInterval_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrInterval.Tick
Dim myFile As New IO.FileInfo(FilePath)
If myFile.Exists Then
...
...

I want something like this:

Public Class Form1
private myFile As New IO.FileInfo()

'but I do not have strMessageFilePath value yet, that will be achieved in form load.