Timeline programs are something I’ve looked at from time to time, but none of them really fit my bill. At this point I should say that I haven’t looked at Aeon for a long time, and I’ve just d/l’d the 20 day test copy for a new evaluation. But my favourite timeline software is a combination of a) my Mac Calendar and b) LibreOffice’s Calc program (no doubt MS Office Excel is just as good, but costs more).
On sheet 1 of my spreadsheet I have a table of the principal characteristics of my various important characters (and some of the minor ones). These include forename and surname, date of birth, colour of hair and eyes, height, weight and BMI (height and BMI are usually the deciding factors, and weight the dependant factor), job, where they live, and relations, that is father, mother, siblings, partner and in some cases other relationships.
On sheet 2 of my spreadsheet I have a column for the dates of important events in the first column, the day of the week in the second column and the event in the third column. An event can be merely someone’s birthday. In subsequent columns I have the principal characters and their age at the time of the event - this can often be an important factor, especially as one of my novels included a number of teenagers, and I needed to know when they could legally learn to drive, buy alcohol, drink alcohol (not the same here in Sweden!) and various other things, including where in their education they were at any particular time. At the top of a character’s column I copy from sheet 1 their name and date of birth, and then have a simple formula to show their age in years and months in the rest of the column, beside each event. It’s easy to add a row or rows wherever I need, and relatively easy to move a block of events to a new location and merely change the date column.
In Calendar I make a special calendar with a distinctive colour - I’m usually working a few years in the future so normal calendar events don’t tend to get in the way - and make entries in the normal way for my various characters. I find a calendar is a better way of picturing time spans so that, for example, a woman who gets pregnant in January does not give birth in April and not in December either, and it helps one to provide a reasonable period of time for different events to take place, for example if someone sends a packet abroad, when can they reasonably expect a reply by a) email, b) snail mail, and c) by someone sending a packet back.
It works for me, and may well continue to do so until the perfect timeline software comes along.