Personally, all I need from a timeline is a simple, sorted list of tasks. What I have is a filtered view of a set of tasks, sorted by due date (all my tasks have a default due date, specified in a template, in year 3000, so they are sorted at the end, unless an actual due date is specified). I filter for only tasks with a due date in or before 7 days from now for a week timeline, and in or before 31 days from now for a month timeline. The only problem I have with this approach is that I have to specify an actual due date in two steps: setting the due date to today so that I get the calendar picker for the current year, and then set the actual due date. Otherwise, works perfect for me.
Nevertheless, I love how you solve these kinds of issues with simple, yet clever and usable designs. This is an amazing idea I might utilize just for the fun of visualizing data like this.
I like your approach about solving this issue, especially the year 3000 one, I have always struggled with non-dated tasks appearing at the beginning of my list.