In my current Byz game (normal difficulty, 1399 start), which I need advice on and will post another thread soon, it is 1503 and I have taken all the cores back, own all of southern Russia from Cherson to Sarai/Astrakhan and north to Tenbow/Kharkov. Asia Minor, the East med coast and Egypt are all mine except for Gaza (haven't bothered yet). All the Caucasus/Armenia area is mine except 2 province Georgia. I am in the middle of a massive war with the Jailiarads who own the almost the entire Arabian peninsula, half Persia and all Mesopotamia and Damascus. Venice (1 province), Serbia (2 provinces), Wallachia (2 provinces) and Ukraine (8 provinces) are all allied vassals. I had to wait until well into the 1440s before I could take the Ottoman provinces. The Timurids were eviscerated by the Mamelukes so couldn't hurt the Ottos. I took the Turkish minors and then spent the next 20 years being attacked by Qara and Algiers, yes Algiers. Eventually the Ottos made a mistake and took Silistria giving them a border with the horde. A quick GH invasion and I took my shot annexing 5 asia minor provinces and it was off to the races. The thing with the Byz is that you need to wait for an opportunity and be prepared when it happens. Pushing too early just gets you dead.