I took a pretty unconventional route when I started a few years ago and didn't bother touching Phoenix for a long while. Sure Thrawn is awesome, but even back then having a Phoenix squad eating up a big chunk of your GP at low levels isn't ideal. Honestly going Separatists early is a great idea in my opinion it allows you to work on a great defensive team with Nute, an amazing all-around team (particularly early) with the Geos, and one of the best teams in the game in Padme.
You want to work towards GAS, but that requires so much including Ewoks for 3PO, a ton of ships, and more. I'd say go after one of the Revans first (JKR will give you a real nice Sith Raid team too), but I also say go after Clones too. They will allow you to dominate the Sith Raid and work well both offensively or defensively. But overall, don't be pressured to go after Phoenix and Thrawn. The game is way different than it was 2 years ago when that's what everyone did.