I just reached 8k followers but I noticed growth hasn't been linear. My "follower-per-tweet" ratio has grown nicely in recent months:

Aug 1.33 (575 followers, 432 tweets)
Sep 1.29 (692/535)
Oct 1.39 (432/311)
Nov 1.60 (473/301)
Dec 3.24 (748/231)
Jan so far 5.66 (181/32)