Shinkasen from Kyoto to Tokyo on April 27

We are planning to leave Kyoto for Narita Airport on April 27 via one of the Shinkasen (Hikari or Kodama) trains in the morning to catch a flight that leaves 5:30 p.m. We will have a JR pass so cannot use the Nozomi trains. Should I be worried of not getting on one of these trains since it is so close to the beginning of Golden week? We can't make seat reservations until we arrive in Tokyo on April 16 (which I fear all seat reservations will be taken by then). Should I just leave Kyoto one day earlier? Thank you in advance for any answers.

To be honest I think you will get a seat pretty easily. I would definitely take an Hikari train and not a Kodama, the Hikari will get you to Tokyo in much less time. I would try and book your ticket once you have your JR Pass but I'm sure you'll find some seats especially has you have a bit of a time window (ie could take a slightly earlier train). I would not try and book for the day before unless the trains were completely sold out, which seems highly unlikely to me. Even if they are sold out you can always take a non-reserved carriage, and/or stand for parts of the journey.

I think you will be fine though!

Enjoy your trip!

You will have absolutely no problems making a reservation for April 27 if you arrive on April 16. Many trains will not sell out at all on April 27. This year, I think that only May 5 and 6 will be very busy in direction of Tokyo.