The first issue was sent out to 10 subscribers.
I've created a simple signup page, shared it on my Twitter profile, and got a few initial subscribers.
The first two issues were named Alpha & Beta, and both were sent to about ten subscribers. The third issue, Issue #1, was sent on March 26, 2012 to 279 subscribers.
At the time I started CSS Weekly, there was not a lot of technical newsletters in circulation. This helped CSS Weekly get some shares on social media, which resulted in initial growth.