Pontus is a fun faction, but tricky to speedrun. This took a lot of trial, error, and resetting, and has plenty of room for improvement.

1. Start can be tricky because of the potential of Armenia, Colchis, and Galatia to declare war early. Galatia can also complicate things if it decides to build food in the city so it doesn't suffer attrition, in which case you'll need to send a second army in to help deal with it.
2. Public order is a significant issue in the East because of the lack of Greek Culture, and slows down military progress a lot. It may be less of an issue if you expand westward in the start, but that would also eliminate important allies in the East like Rhodos, Pergamon, and Bithynia, and would place most of the task of expanding there on the player. Declaring war on the Seleucids early may be a more practical play, but will require a couple of decent armies of hoplites, as the Seleucids wipe the floor with Eastern Spearmen. Could also create problems with Cyrene getting too strong and muscling in on Seleucid territory.
3. A lot of luck can be involved that can either save or cost you time at the end. Egypt struggles a lot against Kush and it is not uncommon for almost all of Aegyptus to be lost to Kush. It's worse if Egyptian client states end up reconquering parts of Aegyptus, forcing you to declare war on them. Baktria can vary a lot. I got lucky with a very strong Baktria game, as some games by the time you expand that far East Baktria is on death's door.