I've always found the Points books available fastest in the UK through Book Depository. The link will take you to the book, though without the cover and not coming up clearly in a search (ack - hope they fix that!). It's also available at Amazon.com (same time-delay) - though oddly I've never been able to get the new Points books through Amazon.co.uk, though the other three come up as available now (Amazon.co.uk seems to use its BookDepository outlet for them when they're first published).
Hopefully there'll be just time for a re-read of the first three books before my copy arrives. Hooray!