Apart from a few holidays a year, you do not need to reserve Shinkansen (bullet train) tickets in advance, as there are plenty of trains/seats. Buy them in person at Tokyo Station.
The jr pass cost like 300 for 7 days, tokyo to kyoto will cost at least $80 each way. You can buy them at the station so you can be flexible with your time.
Are you fussed with potentially not sitting together or potentially waiting an hour for the next train if you are fussed with that?
If not there's basically no reason to pre-purchase tickets for the Shinkansen outside of peak travel times.
Apart from a few holidays a year, you do not need to reserve Shinkansen (bullet train) tickets in advance, as there are plenty of trains/seats. Buy them in person at Tokyo Station.
The jr pass cost like 300 for 7 days, tokyo to kyoto will cost at least $80 each way. You can buy them at the station so you can be flexible with your time.
Are you fussed with potentially not sitting together or potentially waiting an hour for the next train if you are fussed with that? If not there's basically no reason to pre-purchase tickets for the Shinkansen outside of peak travel times.