This is all kinds of exciting.
It appears he joined yesterday and at this time this was posted Chappelle had already amassed 116,000 followers. Though he's not verified, many celebrities (including Aziz Ansari) have suggested it's the real deal. Here are all of his tweets thus far:
Source: @chappelledavidk
Source: @chappelledavidk
Source: @chappelledavidk