The concert starts 1 hour after
Meeting will finish 10 minutes
I will do my homework next lesson
In + time to Start / Finish
Most students can use “ago”. “In” is the opposite.
We use “in” to talk about the time remaining before an event starts or finishes.
The concert starts in 1 hour
The meeting will finish in 10 minutes
Christmas is in two and a half months
2017 starts in 6 months
By + Deadline
We use “by” to talk about deadlines. This deadline might be homework, a report, or payment.
I will do my homework by next lesson
You have to finish this report by 8am next Monday
If I don’t see you by 12pm, I’m leaving.