Re: First Time Smoking Baby BacksGost, 2kewl has you on the right path. "3-2-1" actually references spares and BB's won't take that long. Because of important variables like pit temp and fat content of the meat, any cooking instructions based on time alone should be taken with a grain of salt.
Cook your ribs until you see the meat pulling away from the ends of the bones about 1/4" or so this indicates the ribs are ready to wrap. This first phase of the cook will take 2-3 hours depending on your pit temp.
I cook my ribs bone side down while unwrapped then bone side up in the foil. I also suggest the use of apple juice or sauce thinned by 50% with AJ while wrapped, for spares I also apply 3 or 4 nice ribbons of honey along the length of the ribs. The dish shape of the bone side holds the braising liquids (that's what you're doing during the wrapped phase is braising) and allows them to cook thru the ribs.
For BB's the wrapped part of the cook will take 1-2 hours, most likely closer to an hour again depending on your pit temp. To determine when it's time to unwrap, pick up the rack in the middle using gloves or tongs (if you use tongs excercise caution to not pierce the foil). Ribs that are ready to unwrap will be flexible and both ends will sag some(try this when the ribs are first wrapped and they'll still be fairly rigid). Getting a feel for this takes a little practice but you'll get the hang of it.
Unwrap the ribs and return to the grates. This is the time to apply sauce if you're serving your ribs "wet". Check the ribs every 15 or20 mins the last hour (peek quickly to retain heat) and spray with AJ whenever the surface begins to look dry. Cut, eat, grin really big!
Follow your own tastes on what to spray with, AJ is just a really good place to start, I know folks that spray with AJ and bourbon, cola, cherry juice (form marishino cherries(sp)) jalapeno jelly thinnned with 7-Up etc... you get the picture. I use Juicy Juice brand apple juice concentrate that comes in a 12oz soda can. The juice concentrate combines with the rub on the ribs and makes a sauce-like glaze of its own.