The rides are self-directed, you can start and finish whenever you want. In the past, most groups meet up on a Sunday afternoon and converge on the rally on Wednesday.
This year will be a bit different, given that the rally location is so urban.
On Tuesday night there will be a place in the St. Croix State Forest where everyone will converge. This is a couple of hours (depending on the roads you take) northeast of the rally, with really nice dual-sport riding in the vicinity. The thought was to spend half a day riding that area with no luggage, then head down to the asphalt jungle.