How to ignore cell if first value of the cell is specific character VBA code

Hi guys i am new here and new to coding !

I am using the following code but want to leave or ignore the cell if the first character in the cell starts with "3" only else the below code should work on every cell till the end of the column where data is present

    For p = 2 To end
    If Len(Range("AE" & p).Value) < 5 Then
     Range("AE" & p).Value = "00" & "" & Range("AE" & p).Value

End If
Next p

Can you please help me with this