aging in a whisky barrel

Transferred my oatmeal stout today and am wondering how long to leave it....this is a fresh barrel that hasn't had beer in it before today.

The other barrel (rum) will get a chocolate/coconut porter soon!

I would recommend tasting the beer after a week using a wine thief. The small barrels have a very high surface area to volume ratio and do not need long aging. I have used two rum barrels and the first use of a new barrel for me was between 7 and 10 days. Bigger beers can handle a bit more time. The second use of the barrel will need to be about twice as long and I have been able to reuse 3 or 4 times before turning them into sour barrels. I put a bottle of rum in them and rotate the barrel every few days in between beers to keep the barrel from drying out.

Cheers!