Kernel 5.3 was released upstream yesterday Sept 16. Fedora will be following the
same rebase schedule as with past kernels. This means F30 will be rebased to 5.3
first followed by F29 shortly thereafter. We typically wait until the 2nd or 3rd
stable release to push a rebase. Based on past timings, I'd expect this to happen
around mid-October. You can find test builds in the kernel-stabilization COPR.
Note that F31 will be shipping with 5.3 so you can always test those kernels too.
Please also keep an eye out for the 5.3 test day which will happen before the
rebase as well.