I started with the Blood of Kerensky Series which starts on the BT timeline at 3050 then I moved on to the Twilight of the Clans series and followed that with individual books in as close to sequential order as I could get In total I have read 25 novels finishing with EndGame. There are a few holes in there that I am now trying to fill in. If you want to start reading BT then a good source is the used books on Amazon.com.
I find the 3050 to 3067 date range to be the best because there is so much going on. For example: Clan invasion, Victor Davion-Steiner, Com Star, Battle and truce at Tukayyid, Clan Wolf split, Natasha Kerensky, Phelan Kell, Clan Wolf, Jade Flacons, Davion-Steiner civil war and the list goes on. There are many story branches.