How long after E.T.s attack Earth should we respond? How much time would it take Earth to come up with a plan

A plan such as to first try and study their technologies, then to somehow negotiate with them.

How much time would Earth have until we would be wiped out by an alien civilization that is a million years more advanced than us?

How could anyone possibly answer this?

Aliens a million years more advanced would not even have to show up or get close to the planet to attack ... and humans may not be capable of even identifying where the attack is coming from.

An alien civilization with advanced technology could easily nudge a large asteroid along a path to hit the planet and destroy it without us even realizing doom is on the way.

We would likely not have a chance.

It really depends on how advanced they are. If they aren't too far ahead of us we might be able to fight them back for a while. If they are far more advanced then us, they could wipe out human civilization in a few hours. It also depends on their body type and biological needs, i.e. if they can breathe in our atmosphere or not without technological help. Their armor and weaponry would probably be the biggest factor on how much of a chance we have. As far as negotiating goes, they would probably rather just eliminate us instead. Or they could become an intergalactic ally and trade their technology for our resources and such.

If they intend to wipe us out there's probably no point in worrying about how long it would take. If they arrived from another planet to achieve this mission, they would be more advanced technologically than we and presumably any efforts we may apply would ultimately prove to be futile. The best thing would be to attempt to negotiate with them and compromise.

Think carefully.
We have the technology to wipe out the planet, but can't even travel
between planets yet.
If they have the technology to get here from another star, and they attack,
... there isn't going to be any response.

aliens, have helped us build our civilizations, i mean ask yourself. how were the pyramids built when they barely had any technology they always have helped us maybe we think they are evil but im not sure how long it will take for them to destroy us xD