Така, първо yet и already означават вече, а just - току-що; но и в двата случая изреченията не могат да станат с тях.

Ето ти правилните преводи.
I haven't phoned home since Christmas.
We have been here since 9 a.m.
I have been working for them for more than 8 years.
I haven't visited my home town since I left school.
I haven't gone to (the) cinema for ages.