I'm currently Paragon level 8, nearly 2 weeks after 1.04 came out. By my estimates, I should be able to hit level 100 sometime March or April next year at my current pace provided I don't get bored and move on to something else by then. >_<
Running Inferno A3 all the way through is probably the most natural way, since that's a good way to farm as well. If you are trying for the most efficient way, just pick a route that has a good 15-20 ellite packs and run it a bunch.