Typically, Microsoft releases a new Windows 10 Insider Preview build to the Fast ring every week, or at least that's what the Insider team aims for. In fact, the Slow ring should be monthly, despite it's unreasonably slow pace.
But as can often be the case, this week's build has been canceled, due to a blocking bug. This isn't all that uncommon, but if you've been checking your machine for updates religiously at 10am Pacific Time, you can wait until next week. In fact, you can probably wait until at least Wednesday, as Monday and Tuesday are usually reserved for testing.
New Fast ring builds have moved from the RS_PRERELEASE branch to the RS5_RELEASE branch, meaning that the team is beginning to wind down development of new features, and it's focusing on fixes as it prepares for a final release. The update is expected to be finalized in September for an October general availability.
One feature that's still missing is Your Phone, an app that will allow users to send and receive SMS messages from their device, and even browse the photo library. If it's not released to Insiders soon, it might end up being pushed back to the next feature update, codenamed 19H1 for the first half of 2019, just like Sets.
Either way, make sure to check back next week for a new Fast ring build.