If you leave at 8am it should take about 35-45 minutes.
Just curious but what differance does it make if you leave at 8am? Does it take longer if you leave a 9? Wouldn't it always be the same amount of travel time?
Well, trains come at less frequent during different times of day. And also, at rush hour, trains take a little longer on the trip, since there are more people getting on and getting off.
Unfortunately, on the MBTA, they don't put much stock in schedules, and getting anyplace on time.
Just curious though, why not drive to Quincy? Parking is no worse in Quincy than it is by Davis (in fact, I think its easier to park in Quincy...although perhaps you should be a little more careful locking your car), and if you take the right routes, it shouldn't be a longer drive than train ride. I certainly understand if your not used to driving through the city, I just avoid taking the T at all cost...if I am going to be late, I feel better being stuck in traffic, than sitting in a train with no clue what is going on.