AT, IN, ON in time expressions

We are going to be on a beach on the coast (a)   four months.

If you want, we can meet (a)   dinner time and talk about it.

I am usually very busy (a)   the morning, so please call after 5PM.

Are you free (a)   Friday night? We could go to a party.

(a)   just a few minutes the people will see who the new president is.

She was born (a)   September 5th 1986.

I prefer to do this course (a)   winter, as I do not have anything else planned.

I prefer to study during the day but my brother would rather study (a)   night.

I still don´t know what we are going to do (a)   Easter. Hopefully something fun.

I need to have this project finished (a)   Monday morning or I will be in trouble.