Originally Posted by
atl runner
Pre-Check--great.^ Delta, of course, so that would be Terminal A?
When will the traffic start getting bad on 90 east? I'll just go before that. I was in Carlsbad, CA recently and after experiencing Southern California traffic up from SAN to Carlsbad, I left Carlsbad on a Monday morning at 03:45 to beat the traffic on the return--and it worked.

I'd say you'd be safe anytime before 6AM. It wont be bad really until the 95 interchange.
And yes, PreCheck is at Terminal A. According to DL.dumb, "Boston Logan International Airport
(beginning 6/19/12)
Terminal A"
http://www.delta.com/content/www/en_...-precheck.html