I've grown one photo DP BB back in the day and also first auto one was a G13 BB, each started off funky, slow , a few deformed leaves to start than they each took off.,.. Like ya said they were slow starters. Your BB your trying to sprout can you see the "shell" out of the soil? Maybe it needs a little help, try gently removing it Possible... I can tell ya the BB is one great smoke! Smooth inhale medium expansion in lungs smooth on the exhale. I let mine go bout 20% amber, almost narcotic strength in for someone like me with a very high tolerance a blunt will give me 3-5hts solid rest... Unfortunately my crop of it is almost gone (yield about 1.5/2oz can't remember ) enjoy your harvest! You'll be very happy!
Yoda