"Моя тётя собиралась всё постирать ещё вчера."
Translation:My aunt already planned to wash everything yesterday.
"еще вчера" is used in one of the two meanings: (1) as recently as yesterday, (2) as early (as far back) as yesterday. In the first case, the English will be "My aunt was going to wash everything as recently as yesterday (but then she changed her mind an now she doesn't want to the washing after all). In the second case, it will be "My aunt was going to wash everything as early as yesterday (so she is likely to do it any time now)". "already planned" is not in the Russian sentence.
Спасибо большое за инфо. I came to the comments section because I got the answer wrong and I was really confused about whether this meant that she had planned to wash everything yesterday (as in finishing everything on that day) or that yesterday she made plans to wash the clothes, and the word order in Russian gave me the impression that it was the former.