Yep, your "haves" list are plants that you will/can bring to the swap. I gave us a few weeks to get our lists entered as we start looking around the yard, before we start on the process of calling dibs. For the seed swap, I started in on the trading too quickly, while we were still trying to get the hang of the Seed Swaps tool.
Whether you dig a plant a few days before and just put divisions in grocery bags or pot up smaller divisions asap all depends on what kind of plant you are sharing as well as on your own time constraints. You can describe what you are bringing in the "seeds per packet" field as well as in the comment section for the plant. Although the Seed Swaps tool could have a number of changes made to adapt it to plant swaps (as discussed in the ATP forum), I think it should be pretty usable as it is. :-)
People can still sign up once trading has started... I just need to let Dave know, and he'll manually add their name to the swap. (Down the road, he might add options like that to the swap host control panel, but for now he'll just do it directly.)
