I agree about the pre-AH stuff except if it pertains to your sole property. That said, I made a timeline for my lawyer and it was very helpful. It was written in two columns - date or date range in the first column and the event in the second column. It included things like when we met, first started dating, got engaged, but also major financial decisions. And, it got more detailed the closer it got to the present day. Yes, it was painful making it, and it set me back for at least a week. I was sifting through a lot of email communications and bank records to try and get an accurate timeline. I came to SR to let out a lot of the feelings that process dredged up.
Here's how it was helpful... My lawyer never had to ask me any questions related to the timeline again. She had all that complicated info at her fingertips. When she sat down to write a brief, SHE was the one who got to summarize this chain of events and I didn't have to think about if she got those dates right. She had the timeline. While I was at it, I had also created a folder of all the communications listed in the timeline. I just gave her that folder as my supporting documents for the timeline. I've never had to open that folder again. She has that info. It's like cleaning house and putting out the recycling for someone else to deal with. She turned all those empty broken bottles into something much more productive. All I had to do was sort the brown glass from the green - time-consuming and bothersome, but doable.
Hugs, WTBH! It can be an overwhelming task, so try to separate it into manageable chunks. I started with making a bare bones skeleton of a timeline (major life events - births, deaths, marriages, etc) then filled in additional bits as I saw fit. You can stop and call it done anytime you want to. I could have put so much more detail in there, but I reached a point where I couldn't, and that was okay.
Peace,
Fathom