When I do the reverse trip from around Loch Raven Reservoir to the club, it takes about a good full 80 min CD. Usually a bit longer by a good 10 mins.
Not knowing exactly where you are coming from I'll just assume from the U St. corridor area, I would say it would be much shorter because you won't have that additional 30 mins or so that I have just getting into downtown Baltimore BUT you will be dealing with a lot of leaving DC rush hour traffic. I'd say to give yourself at least a good 1 1/2 hours to play it safe. If you are lucky, you will get there with time to spare. But I wouldn't even dream of cutting it any closer than 1 full hour unless you don't mind the stress and missing a little of the front end of the show.
Also, I don't know what's going on with parking around there now as I haven't been to the Meyerhoff in years so you may have to circle around and get lost in the weird mess of streets in the area. It's like DC goofiness in that neighborhood with all the curved and 1 way streets. I suspect that there's some place that will allow you to park for tons of money but I couldn't swear to it.