It was after college, when I was in my first year of architecture school, and miserable, that Damon and Dean started talking about reforming a band. I thought that sounded like fun and volunteered to play bass
Naomi Yang - Temperature's Rising: Galaxie 500 an oral and visual history (p16)

Galaxie 500 was born the day that Naomi volunteered to play the bass guitar
You can spend your time placing ads in the Village Voice and sifting through messages on your answering machine by idiot musicians […] but the best thing is to start a band with your friends. Your friends are tasteful and smart and like the same things you do. Who cares if one of you doesn't play an instrument? She can learn.
We had our first rehearsal on May 27, 1987
Dean Wareham - Black Postcards: A Rock & Roll Romance (p33)

MP3: Pride - Galaxie 500 (1987 - extended demo cassette)

* OK, there's a receipt for Naomi's bass guitar in Temperature's Rising that's dated 2nd May 1987 which suggests I may have to revise Galaxie 500's birthday... AGAIN!