You can incorporate a timeline in many ways. TheBrain 8 offers a new Timeline View, that gives you a chronological display of the previous 1000 created and modified Thoughts.
In terms of task management, you can use the checkbox feature in the Notes section (in notes you can insert a checkbox by selecting Insert > Insert Checkbox) to insert your task with a checkbox next to it so that you can check off your task when you have completed it, you can set key time based priority Tags. There is also a built-in calendar for scheduling tasks and key due dates associated with your Thoughts.
Here's also a nice overview on using TheBrain to manage tasks and projects: