We may be sounding like a broken record at this point, but Windows Insiders won't have a new build to play with today (Monday 12/18.) This is according to Brandon LeBlanc, who provided Insiders with a status update, saying the team is working hard to get a new build out "soon."
Just an FYI for #WindowsInsiders - no new build today. We're working hard to get one out soon though!
— Brandon LeBlanc (@brandonleblanc) December 18, 2017
LeBlanc is not giving any promises, but he did say in a subsequent tweet that the Insider team is trying and "soon" could mean "this week." This build is also set to include Windows Timeline and Sets, two hotly anticipated Windows 10 features. As you may recall, Dona Sarkar previously revealed the upcoming build is very important for this reason, and Microsoft wants to ensure the best possible experience for everyone.
Anyway, it's best to let the Insider Team do their work, as the last thing we would want to see is a build that breaks the PCs of those opting to install it. Patience is a virtue, and it all will pay off when you can dive right into Windows Timeline and enjoy all of its features without bugs or issues.