Oh dear, yes, the accountant-part...
Personally, in my journal I just started with where I was at that point in time (with a short introduction) and here and there I explained something more about the past, while mostly talking about the present / the last month, etc.
But given that you're an accountant ... You might want to start with a table of contents? This can actually be done on this forum, as you can go back to the first comment (the table of contents) and edit it. So you might want to create a table of contents like your life in chronological order (Early years - high school - young professionals - your 30s - your 40s - your 50s) and then you could add references to where you discuss these parts of your life more. (References as in: "see page 3", or "see 3 Dec 2016", but you can also create links to specific posts).
Unfortunately, you can't "sort" posts - so if you report on your 40s first and only later about your 20s, then that order in your journal is fixed. Although... you do have the option to delete a specific post; and of course you would be free to copy the content of that post to a new post. That could be a way to move the contents of a post forwards in time. But... why would you do that? Ha
It is also perfectly allowed on this forum to have a diary just for whatever occupies your thoughts at that moment, and to build another diary or thread elsewhere that's more structured, or has a specific theme. So that could be another thing to do. Make the diary strictly about the here and now, and create another thread to report about the past.