If (dateTimePicker's date is before this month) then... else

I'm busy making an application in C#. No code yet but what I need to check is if the month in dateTimePicker1 is before this month. If the month in dateTimePicker1 is before the current month it needs to close the app.

Basically what I need is this:

if (dateTimePicker1's month is before current month)
{
    System.Environment.Exit(1);
}
else
{
    //do nothing
}