In an earlier version of the Baker House timeline, we repeated the long-believed factoid saying that
when Building W7 (a/k/a the "New Dormitory") was first occupied in 1949, it was restricted to Seniors.

However, Tom Jannsen wrote specifically to bust this Baker House myth:

In the timeline, it states that the New Dormitory opened in September
1949 but was restricted to Seniors. This is incorrect. I and many other
Sophomores moved into the New Dormitory in September 1949 and stayed
there for three years until we graduated in June 1952. Perhaps the MIT
administration took pity on us because for our Freshman year we were
housed in a dilapidated building [the Barracks Dorm, also known as Building 22] twelve to a room.
Tom Jannsen
SB 1952, SM 1961 

As did Werner Kahn:

I am from Class '52 and was the first official resident in Rm 140 when the Fall semester 1949 started.
I stayed in the same room thru graduation in '52.
Werner Kahn
II, '52 

An article from The Tech in that timeframe says that preference would be given to housing Seniors in the New Dormitory, 
but it doesn't say that the New Dormitory was restricted to Seniors.