Timeline updates through button automations

I have a simple task… I need few button automations that set start or end dates of timelines, or a start date in a field (but clicking it later doesn’t change that start date). For my own needs, I need to set the start date of the timeline (or start date field) if it is not yet set, and then also modify the end date of the timeline to the current date. Alternately, I could use a task that sets a column to the current date IF the column is empty.

At the moment, my “I worked on this” button will set the “last worked” date properly, but I can’t automatically set either a start date field or the dates in a timeline.

Context: I’m trying to set up a board for very rudimentary task/effort tracking (as simple as possible, because our people don’t have time for or need a full-blown resource tracking system) with a simple “worked on it today” button that counts the number of days the person has worked on the task (easy, done) and also updates the"first worked" and “last worked” dates (the “last worked” field is also easy, done) for that task.