I agree, a 28 day countdown is too long; if a buyer sees something they want, they don't want to wait that long but I also don't like the 3 days after 1st bid as it puts the auctions at the end of the search pages.
I would prefer either 7 or 10 day listings. It gives enough time for the auctions to be promoted properly without the buyers losing interest.
I also think that later in the month would be better. It takes it away from the YDC and will give all the sellers time to understand what's involved.