Well, if we want it to be Orthodoxy approaching the OTL one, a PoD closer to the schism might be best. Let's see; strengthening the Byzantines would be a good idea. Say, it regains the size it had under Basil II and keep it at that level somehow. This empire could convert the Turks when they come knocking and if the eastern front remains stable, it might crawl towards the Levant and Egypt at some point (or is that ASB at this stage?)
The Macedonian dynasty was a time when the Empire had a resurgence not just territorially, the surrounding polities were heavily influenced in a cultural sense as well. Bulgaria and Serbia were for instance by and large christianised in the 9th century. This was a time when, while the schism hadn't happened yet, Rome and Constantinople fought for conversion to their line of the supposedly united church. Now, Great Moravia had been receptive to the overtures made by Constantinople (look up the request of Prince Rastislav); this was the case for many Slavic peoples, in no small part due to the alphabet Cyril and Method brought them and the fact that the Constantinopolean line allowed for national churches to be established. If we can prevent the fall of Great Moravia to the Magyars, we have a rather large state north to the Balkans which will most likely go orthodox once the schism comes. The Croats had a pro-Byzantine faction too, so with a stronger Byzantine empire, it will be more likely to go Orthodox. Now, if Great Moravia is an orthodox state, this could make it easier for the Byzantines, in conjunction with the Moravians, to convert the Poles: there is after all the succesful example of Moravia just to the south, with its own alphabet, church language and Byzantine political support. Christianisation of the Rus could go ahead right on schedule as well.
Simultaneously, the Orthodox inclinations could be made stronger by weaking the Catholic ones. The best way to achieve that IMO is to butterfly Charlemagne and not have Francia expand into eastern Germany. A lot of soft power would go lost that way, making the Orthodox option politically more attractive too. The Saxons, Thuringians and Bavarians could go orthodox to counter attempts at conquest from the west, where the more deveoped states laid. The eastern brand of Christianity could be seen as the less threatening one. Having an orthodox southern Baltic coast would lead to orthodox Baltic states and - especially with a somewhat weaker west in the absence of the Franksih juggernaut - could take charge in converting Scnadinavia.
While the west would still have a lead in colonising the Americas, this would make orthodoxy be on a more equal footing and visible (perhaps in an alt-Reformation, more will turn towards it?). Then, you could have the Russians be more successful in converting a part of the East Asian populace or a Byzantine empire which controls the Red Sea do the same in India and Indochina, not to mention East Africa.