In my TLs it depends on what I'm going for. For example, in "End of an Age" I've only gone four decades from the POD, but a lot of the figures who were important OTL won't be born (Shapur II, Constantine I, St Athanasius), others who were obsure OTL have become major players TTL (Vaballathus, Victorianus II, Bahram III), and some have had lives similar to OTL (Diocletian, Arius, Claudius II, Tiridates III). Very soon only fictional characters will be showing up (though some might have familiar names). Of course this only applies to the Roman world - China's history has been unchanged so far.
By contrast, my US politics TL, which will come up sometime next week, won't use fictional characters because it will be more interesting to see how OTL politicians are different in that world.