The official ASA postering rules are here.
We counted that if you poster starting at the E25 lobby, work down to 66, 56, 16, over to the infinite corridor (picking up boards on spurs in 6, 2, 1, 4, 3, 7), and the Student Center, this requires just over 70 flyers. In W20 there are boards on the 1st, 2nd, 3rd (1 obscure board outside the bathrooms) and 4th floors. You'll also want more copies for postering dorms, and for Tech Squares members to give to friends. And to reposter each time the posters are cleared.
Bulletin boards at the Institute are cleared on Sunday and Thursday nights (depending on how busy facilities is). People are inconsiderate. My heuristics for "making space" on bulletin boards are:
This isn't a passive business; our presence needs to be maintained. Other groups are much more cut-throat and you
have to keep things up. If I'm walking and find someone has covered one of our flyers, I don't think twice moving theirs. GET HELP. Other MIT-frequenting members should be recruited to police the postering.
Table-top cards in the dining halls now require a reservation to be made at the ARA office, W20-5th floor. By my last count, Lobdell has about 90 tables and Walker has 55 tables. I haven't done Baker and I think there is another dorm-based dining hall in a west campus dorm.
At the beginning of the school year, during rush/orientation up until the activities midway, the ASA limits how student groups may recruit new students. This may interact with early postering you want to do. Check the official ASA rules or ask them for clarification to be sure.