JR Pass confusing info

It says in the explanation in many places that the pass order can be purchased in advance and can then be exchanged for an actual pass within 3 months, the first day of use being defined by the first use. In other places, it says the pass can only be purchased a month prior to the first use. In yet other sites it says that the order must be turned in for exchange for the pass within a month from the purchase date and then should be activated within 3 months... I am totally confused (#1).

More to this: when purchasing via their official site www.japanrailpass-reservation.net they explain that they give just a 10 digit code which is the order code based on which I can the issue a pass but with the start date that is set during the purchase, yet on https://www.japan-experience.com/transportation/japan-rail-pass/nation... they allow choosing any date in future as a start date yet require the shipping address for delivery via FedEx - what do they ship and why at all something should be shipped via the post? (even more confused #2)

Would appreciate simple and clear explanation what should I do if I land in Japan on October 31 and want a pass for the 2 weeks from that date (assuming also that the JP Pass prices raise on Oct 1)

It is explained here:
https://www.japan-guide.com/news/japan-rail-pass-cost-increase.html#ol...

For the three month option - you get a voucher to exchange when you arrive in Japan.
For the one month option - you buy online and can make reservations online (and the price is different).

step A. buying a voucher -(max. 3 months)- step. B exchanging a voucher to a real ticket(pass). you need to fix the staring date(max. 1 month later).

you can buy a voucher from non-official sites. you start from step A.

you can buy a real ticket from JR official website. (no process of voucher) you start from step B.

the websites in your post is both non-official sites. they are merely agents.
if you buy a voucher, and if you have troubles until exchanging it to a real ticket, JR can't help you about troubles between you and agencies.
if you buy a real ticket from JR official website, it is a trade between you and JR company. they will help you to solve troubles.
in both cases, after you exchange a voucher to a real ticket, JR company will help you for using a ticket (pass).

You don't say when you're going to Japan. If you buy the pass at their skyrocketing rates from Oct 1st, it will likely be a money losing mistake for you.

Thanks to all for answers.

We land in Japan on October 31 and leave on Nov 14, exactly 2 weeks, and therefore were recommended to buy the voucher before the price raise on October 1, and we did so. Hope we did right. If we'd buy directly from JR to catch the current price we'd have to buy no later than September 30 and thus having the pass valid for Oct 29 - Nov 11 which doesn't work for us.