New Year’s Cards

Two questions regarding nengajou:

1) Is it alright if it arrives before Jan 1st?

2) If the card does arrive before the new year begins, what is appropriate for greetings? Like, 来年またお世話になります? And would 明けましておめでとうございます still apply?

Ink,
1) Is it alright if it arrives before Jan 1st?
It is quite strange to have a new year's card before Jan 1st. Do you live in Japan? Then, you'll soon see a special post (or special "hole" of a post) for new year's cards.

The post office guarantees to deliver the greeting postcards by the first of January if they are posted within a time limit, from mid-December to near the end of the month and are marked with the word nengajo（年賀状）.

'If the card does arrive before the new year begins, what is appropriate for greetings?'
How about using the following words for your too early new year cards; On condition that you don't put a mark of 'nengajo' on the cards.
The stereo type greeting is;
今年も大変お世話になりました。また、来年もよろしくお願いします。