2. g3 is quite strong against 1. ... e6
I disagree personally. If you are trying to reach the Catalan Opening, which is what the g3 move implies, then 1.d4 e6 2.c4 Nf6 3.g3 is a stronger move order, which is used by GMs. 2.g3 is committing too early to the setup.
Also, old thread 
2. g3 is quite strong against 1. ... e6
I disagree personally. If you are trying to reach the Catalan Opening, which is what the g3 move implies, then 1.d4 e6 2.c4 Nf6 3.g3 is a stronger move order, which is used by GMs. 2.g3 is committing too early to the setup.
Also, old thread
No, I don't think, it's too early. 2.g3 is always good, after Black already played e6, because after e6 he cannot develop his light-squared Bishop on f5. You're right, Catalan is the most probable opening after 1. d4 e6 2. g3, but I personally prefer against Catalan Bb4+ as Black. For example, 1. d4 Nf6 2. c4 e6 3. g3 d5 4. Bg2
a) 4. ... Bb4+ 5.Bd2 Be7 or
b) 4. ... dc 5.Nf3 Bb4+ 6.Bd2 c5!? with equality.
After 1. d4 e6 2. g3 mover order I cannot Play this, because White first Castles, then Plays c4. However, if you Play Be7 against Catalan, it does not bother you.
2. g3 is quite strong against 1. ... e6