I am having some trouble understanding this and some examples would be great. The grammar confuses a bit and sometimes I am not sure whether to use "в" or "на".

I am hoping I can understand this better with some examples.
Is anybody willing to translate?

(I am "throwing in" some other words too, so I can learn them at the same time...)


Future
By next spring I will be fluent in Russian.
He can not afford to go on holiday until next summer.
In the autumn she will take a Russian language course.
At ome time during next winter I will take a skiing holiday in Switzerland.
My sister is coming to visit next week.
My cousin is having a baby next month.
You need to finish this work by next week.
We must continue working on this until next Wednesday.
Unfortunately I will be too busy to see you at all before next Friday.
Next month is January, isn't it?
The Christmas sales will start next week. ("christmas sales"=reduced price in the shops after Christmas; means you can find bargains.)
In the new year I will go on a diet!
During next year I will continue to study Russian.

Past
You should have done that last week, now it is too late!
Last month I had a cold.
Nobody has seen him since last September.
I bought these boots in November.
This cheese has been in my fridge since October.
Last winter I did not get a chance to ski at all.
Last summer the water in the lake was too cold for swimming.
She hasn't been on a date since last spring.
He started studying Russian last autumn.