Reserve seat for May 2023

I will travel with my family (total 6 pax) from Tokyo to osaka and to kyoto during golden holiday week. I read from some article is hard to reserve seat during 28Apr23 to 5May23. My question is can I purchase Jr pass from the official websites now (Dec22) and do online seat reservation for May23 now?

One month in advance.

My question is can I purchase Jr pass from the official websites now (Dec22) and do online seat reservation for May23 now?
You cannot buy the JR pass now for use in May. You can buy within three months of first use.
Reserving seats can be done one month ahead of time, so for GW travel, in April.

And, GW travel is not as bad as some people like to make it sound. It is not like NY or Obon when travel is crushed into a few days. Be flexible on your times, don't have huge luggage (because of the size limits), and if you are not saving much on the train travel consider not using the pass to have a lot more train options on the busiest parts of the network.

No, u can't.
https://global.jr-central.co.jp/en/tickets/type/date.html

Thank you very much! All of you are awesome, and solved my doubt, thanks again

Don�ft worry too much about GW. The propaganda around it makes it sound much worse than it is.

If you travel on certain days in certain directions, GW can be hell. If you avoid these concentrations, it is simply just a crowded holiday season. In 2023, avoid traveling out of big cities on May 3 and back into big cities on May 6-7: https://www.japan-guide.com/e/e2282.html