C# Test if the actual time is inside a TimeSpan?

I have two DateTimes and a TimeSpan making the difference between of these DateTimes :

TimeSpan Now = DateTime.Now.TimeOfDay;
DateTime start= new DateTime(2015, 12, 21);
DateTime end= new DateTime(2016, 1, 1);

TimeSpan interval = end - start;

if(interval.Days == Now)        //<--It doesn't work
{

}

How do I test that ?