успели собраться внизу.

[Ashatan]

У меня есть такое предложение:
я и не заметил когда эти люди успели собраться внизу.
Можно его перевести так:
I didn’t notice the moment when this people crowded downstairs.
Спасибо

[sledopyt]

I missed the moment (I didn't notice) when these people gathered downstairs.

[yelena.t]

my try:
Before I could [even] notice, all of these people had crowded downstairs

[Василиса]

I did not even notice that these people had gathered downstairs.