using a preposition
can I say "in this year", for example, I wish you all the best in this year?
most grammar books say we don't put prepositions of time before "this", but I've found some examples at BNC, I'm confused (

Question

using a preposition
can I say "in this year", for example, I wish you all the best in this year?
most grammar books say we don't put prepositions of time before "this", but I've found some examples at BNC, I'm confused (

Answer

Right.  It is also correct to say it without the preposition:  "I wish you the best this year".

And I, personally, would opt for using "during this year" instead of "in this year".

Answer

You could say: I wish you all the best this year. Or you could say: I wish you all the best this coming year. But I wouldn't use a preposition here. 
But we do use a preposition for 'at this time' for example.

Answer

It's OK. You may say "in this year" or "during this year". The preposition might emphasize your good wishes.