Latest possible purchase time before price rise

Hi

Are we able to buy the 21 day pass on the 30th September / or have it issued at this date ( last purchase date before price rise you have as 28 Sept )

I see that yes the 30th is a Saturday but as we are arriving in Tokyo 29 December this would be the last day for the 90 day period of activation ?

Also I have seen on other info online that the exchange order can be issued a month before arrival and as such this would be the start date of the 90 day period to activate ?

Many Thanks in advance

Brad