Grammar: Prepositions "in" "on" and "at" (time)

You use "at" with:

clock times	at ten o'clock, at midnight
at meals	at breakfast
at festivals	at Christmas, at Easter

With special expressions:
at the weekend, at dawn, at night, at the moment, at the time, at the end of the month

You use "in" with

parts of a day	in the morning, in the evening
months	in January
seasons	in the spring, in winter
decades	in the sixties
years	in 1999, in the year 2002
centuries	in the tenth century, in the last century

You also use "in" to talk about when something will happen in the future:
I'll talk to you in ten minutes.
He'll be at the top in a few years.

You use "on" with

days	on Tuesday, on Thursday
parts of a specific day	on Wednesday afternoon
special days	on Christmas Eve, on Good Friday
dates	on Friday 13th
on special occasions	on my birthday, on our anniversary

When were you at the disco?
on	Monday 23rd. September Christmas Eve Saturday night my birthday Friday evening	at	the weekend Christmas 10 o'clock dawn night Easter	in	September 1994 the morning, the afternoon and the evening winter the winter of 2004