I've been asked this twice today, so let me post here in the vain hope that somebody might come across it. While the schedule for Smalltalk Solutions isn't up yet (real soon, I promise), the basic schedule is that the conference talks happen over three days, Thursday through Saturday. That's June 19-21. On June 18th, there'll be registration open, some coding contest activites, and a welcome reception - so basically it's the day before the conference really starts. If you're looking to book travel, you want to arrive on Wednesday. It's not necessary to arrive on Tuesday.
I knew this would be confusing.
Oh, and we've got some really good talks lined up, and I think it's going to be a great conference.