NRT to Kyoto - Seating Availabililty with No Reservation on a Friday Night

Hello - I will arrive with my family of four in November at Narita during a Friday evening. That night, we will stay in Kyoto. My understanding is that I cannot book a train reservation for my JR Pass until I am in Japan. So, I wonder, is it likely given our arrival time and onward destination, that we will be able to secure seats via Shinkansen without any advanced reservation? I wonder if that is possible to do on a Friday evening. Thank you.