After Manaan and Alderaan are complete - next objectives are Corellia, Ruusan and Bilbringi.
If the One Sith gets frisky and hit Corellia as I suspect they might, shift attention north to Tython or Anaxes. Strategically - you're cutting them off. We could even hit Eclipse to box them in and force them North towards Fringe space.
Roger, roger?
We cannot or rather do not want to engage them directly in an Invasion - unless we absolutely have to. Looking at who is left out - they have alot more heavy power than us, even with the Force being wonky and such.
I mean, it's totally up to the leadership but I think engaging prematurely is suicide and pointless this early on.