How long you spent on the assignment.
About 2 hours

What you like about your implementation
Pretty much all of the logic is in pure utils, so it can easily be tested. It is not "compact", but I felt that wasn't the way to go for a timeline; if the space between events was condensed then it would not properly show the scale. It is responsive. It could be adapted into an agenda view for an actual calendar.

What you would change if you were going to do it again.
There's a bug I didn't get to fixing :). Styling is minimal right now. Some optimizations that I skipped to save time. I just made a "hack", for white space between events that relies on adding empty divs, it should just use margins or a single block with a calculated width instead. It should really use a memo since these calculations aren't the cheapest.

How you made your design decisions. For example, if you looked at other timelines for inspiration, please note that.
It was kind of hard to find an example that didn't look like a gantt chart, which would have taken up more space. But I realized it's really just a calendar view, so I looked at what iOS does for multi-day views on their calendar.

How you would test this if you had more time.
I isolated most of the logic to a utils file and broke it down into steps, so each one can be tested using unit tests pretty easily.