Sorry, but I have to say it - countries don't announce the dates they are going to attack someone, it would sort of defeat the element of surprise, don'tcha think?

Most countries don't actually tell people when they plan to invade somewhere else. They keep it a secret so they can surprise the other country and have a better chance at winning. If they announced it ahead of time, the other country would just prepare by getting troops ready, making defences, and finding allies to help them fight back. That makes invading way tougher and historically keeping military plans secret has helped attacking countries be more successful and lose fewer soldiers.

There's also the fact that nowadays, the UN and international laws look down on countries invading others without good reason. If a country told everyone they were planning to attack another country, there would probably be a bunch of criticism from other places around the world. They might get punished with economic sanctions or even have other countries threaten to fight them to get them to stop.

So basically, for the military and politicians it's really important to keep invasion plans under wraps. That helps increase the chances that the invasion succeeds, and reduces the chances of causing a major global controversy over it.