Thanks for all the replies! I have to sound like an idiot for a minute here: I tried flaking the sail down before, and it really seems to slide around everywhere. I can't get the folds to be even, and the battens run at about a 30 degree angle from the folds. It really seemed difficult; I know I'm doing something wrong though. I tried lowering the halyard gradually while I gathered up folds, and single-handedly, this didn't work too well (my sail has a rib to hold it into the mast track, not separate sliders). When I take a bunch of sail down, I just have an unruly pile to try to flake. I may try Tenuki's burrito method!
All the other advice made perfect sense to me! My plan is to go from the dock out onto the lake for a while and practice some motoring to get a feel for the boat, and then when the marina looks quiet, begin trying to dock it in the slip. As long as it doesn't start taking on water, I think I'll be okay. I will probably have a hundred questions after the first day, though!