Craggles - I'll echo Vroomfoggles comment that you will initially find the timeline overwelming.
The timelines that are in 'modules' rather than the atlases all include pretty specific information pertinent to the area that module covers. i.e. Haalkitaine talks a lot about Rhakhaan nobles and wars with Urulan, Xa-ar tell you a lot about that specific region, etc.
So Atlas IV or Vroom's library (filtered) is a good place to start.
Personally what I did was paste the entire timeline into a spreadsheet and organise it in a way that is meaningful for me.
The three left-most columns are year/season/week
Then I have about 20 columns that are each themed, such as the following:
.........you get the idea......some of tghe columns focus on very powerful individuals, who I won't mention here to avoid spoilers.
And then I moved every timeline item into the column that matches it best. This might sound like a lot of work, but it was certainly a good way to learn and get familar with the timeline as a whole, and because I tend to think in 'building blocks' it is also really useful for me visually - I can scan down the spreadsheet and quickly see where there has been a concentration of events in each theme.
For planning purposes it is invaluable to me as a GM
I have a column called "PCs" where I write in what the PCs do as they do it so it gives me a ready-reckoner of what has happened, but more importantly I write notes in the boxes in the future (in a different colour) to 'script' upcoming campaign events, which makes it really easy to co-ordinate campaign activities with world/local events that are upcoming in the timeline.
Occasionally it shows-up the need to move 'canon' timeline events to better suit how the campaign is evolving as well!
Then each time a new module comes out (like Xa-ar) I work through the new timeline and copy the new bits into my spreadsheet - again a really good way to get familar with the timeline in each new book.
Final note - you will I'm sure have noticed a rather unique feature with Terry's world is that with each new module/book the timeline is detailed a little bit further into the future, and each module also tends to be set at a slightly different period in the timeline! As I say, it's kind of unique and it means we all learn a little more about the future with each new publication, and it also keeps the whole thing very live and dynamic.