I would count on a long day - leave fairly early in the morning to arrive before dark. Sounds like you are doing this for the first time - be VERY wary of ships in the channel. They are going a LOT faster than you think they are.
In a Hunter 30, I don't think you need to worry about the spoil banks charted on either side of the ship channel. Needless to say, be aware of the weather before going out into the middle of Mobile Bay. Most times I wouldn't consider it dangerous, but I have had a couple of uncomfortable crossings, and that probably wouldn't make a very good Valentine's present. Have fun at LuLu's!