Wrong. If you listen to the news in-game, it takes place after the BM Incident, portal storms everywhere. While this could still mean that it takes place before Freeman finishes in Xen, it also says Dr. Breen is touring the country, giving speeches about what happen. That implies it’s been a bit since the BM incident. Listening to the Vortigaunt when you go to the slow-motion bit, it seems like this is the time the Vorts are trying to contact the human race, while the humans are still seeing them as enemies. Since they are being fired on, they are fighting back. This is why the first vort said you were ‘misguided’.
It also seems that this takes place just before the 7 Hour war. You have a few mercenaries that look similar to the combine uniform, while apparently having their own mysterious agenda. Also, while listening in on their radio channel, you hear a weird sound, which to me sounds like the sound advisors make. And also, while everyone is sort of used to portal storms, there are now much larger portals than before, something which happened in the 7 hour war.