First time sour attempt, how's this sound?

I brewed up a simple brownish 1.043ish, lightly hopped beer that is about 3 days into primary. Bubbling steady (used the Super San Diego yeast just because I had it around), but not a big krausen. I recently purchased a 'bugged' 5 gallon barrel (which smells awesome, sweet vinegar-y).

This is my first attempt at souring beer, being a light beer, I was curious if I should rack the unfinished beer into the barrel so there are some residual sugars for the bugs to start working on? Being a small barrel, I realize that the souring process may be shorter, and to watch for too much vinegar due to oxygen diffusion through the small staves. Should I rack now, or let it finish out?

Not much help here as I've never made a sour yet, but interested in the answers you get. I saw that "bugged" barrel and was going to buy it myself. That is until you stole it from me! Good luck!
tom

I would be concerned about there being too much acetic acid bacteria in the barrel, and turning the beer into vinegar.

The more residuals the more sour. I'd rack it now, if you let it finish it may take a year our more to sour, during which time you may get too much oxygen pickup and acetic production.

rack it now you will have faster souring, but at such a low gravity, you may already be done.

Also you can rack intothe barrel for a few weeks to inoculate the brew, then back to a carboy to prevent took much oxygen during ageing.