I agree that one day a week might not be enough. DD had a friend in her room this year who sobbed all day for the whole year, and her teachers felt that it didn't help that she only attended one day a week. They say you need at least 2 days for them to get used to it.
The breakfast drop off sounds like a good idea. The one time I had to take DD in early she eagerly sat at the breakfast table like it was a real treat, and didn't cry when I left.
Also definitely always let him know when you're leaving, otherwise he'll constantly be worried you're likely to leave him any minute (outside of daycare I mean).
Hang in there and good luck