By eight o’clock Linda will have left.

[Alice Chu]

We use the future perfect simple to talk about something that will be completed before a specific time in the future.
Is the first sentence used more often than the second one?

1. By eight o’clock Linda will have left.

2. At eight o’clock Linda will have left.
(This means Linda will leave before 8 o’clock.)
---from https://www.grammarly.com/blog/future-perfect

 

[emsr2d2]

We use the future perfect simple to talk about something that will be completed before a specific time in the future.
Is the first sentence used more often than the second one?

1. By eight o’clock, Linda will have left.
2. At eight o’clock, Linda will have left.

(This means Linda will leave before 8 o’clock.)
---from https://www.grammarly.com/blog/future-perfect

They both mean she will leave before 8. Using "by" is much more common.

 

[Tdol]

I would use by.