I was talking with my partner about when he would be arriving home and when our guest would be arriving. I didn't know the word for "arrive" and Google translate didn't provide much enlightenment. I settled for "Wann wirst du zu Hause gekommen?" and "Sie wird um 6:00 ankommen" but I have no idea why.
Ankommen vs Eintreffen
There is a difference between
The former one is much more generic, you can also "ankommen/arrive" at a certain state of mind. If the journey was stressful and long, the host will often say to the
eintreffenden (arriving) guests:
"Kommt (or formal: Kommen Sie) erst mal an!"
in the sense of taking off the jacket and shoes, drop your luggage etc. before starting the dinner or other activities.
Eintreffen is (always?) the very short moment of
arrive at a location/scene.
Ankommen can be used synonymously, but is also an activity on its own.
Ankommen vs Kommen
In situations like the one that you described (arriving at home at a certain time) it doesn't matter which one you use.
In other situation
ankommen again means the arrival and
kommen can mean the whole travel, too.
For instance, you have to cancel an appointment today:
Ich komme heute nicht mehr. / I won't visit (you) today.
For instance, you will be arriving tomorrow instead of today, because you missed the last leg of your flight:
Ich komme heute nicht mehr an. / I won't be arriving today.
Wann wirst du zu Hause ankommen?
is just fine for asking someone when the person will arrive at his/her home.
If you live with your partner, you can also say
Wann wirst du nach Hause kommen?
or a bit more informal
Wann wirst du heimkommen?
to ask her when she will come home.
Wann wirst du zu Hause eintreffen?
is fine, but I would consider it a bit too formal for asking your partner.
Sie wird um 6 Uhr heimkommen.
Sie wird um 6 Uhr nach Hause kommen.
Sie wird um 6 Uhr (zu Hause) ankommen.
Sie wird um 6 Uhr (zu Hause) eintreffen.
are all fine as statements (sorted from informal to formal).