Hey Sarah-
Currently HubSpot doesn’t seem to offer a way to filter or sort by the date or time a task was completed; it goes strictly based off the due date. This means if you complete a task early or late without adjusting the due date accordingly, the task will show up on the timeline of the Contact/Company based on when it was scheduled and not when it was actually done.
I usually get around this by just mass updating all of my overdue tasks each morning to the current date, so if I complete it the task will show correctly on the chronological timeline (helpful when the task is given context by relevant emails/calls which are autologged and timestamped).
I also usually put any updates to the task within the body of it with a date, but getting in the habit of updating the due date of tasks each morning seems to be more efficient. 