After the release is before the release. Therefore Leap 15 is being set up right now. tl;dr version: nothing to see yet. Concentrate all efforts on Tumbleweed please :-)
The longer story is that I've just started to copy packages into the openSUSE:Leap:15.0 project. It will take a while to bootstrap and build all packages, as well as getting all tools and bots up and running. So please don't submit anything there yet. Also, this will be a major rebase on Tumbleweed and TW sees heavy changes at the moment. So I'd like to concentrate on having the core package set settled first rather than wasting too much energy rebuilding with 12k packages from Tumbleweed at this point. So don't worry if Leap 15 looks rather incomplete and unusable right now. The goal is to get everything up to Ring2 to build and pass some basic openQA checks. Ie KDE and GNOME default installations. That alone will take some weeks, esp since I will be on vacation for a while starting tomorrow :-) Once we got there we can start adding all the rest again. As announced on the conference the plan for that would be an opt-out model for packages that were included in 42 before (minus packages that got dropped in Factory meanwhile) and an opt-in model for new packages as usual with Leap.