Like others said, it does snowball. Just looked at my stats and as you can see it did snowball however the rate is slowing down some.
Not sure if this is because it's off season (I'm sports related), my niche is pretty small (top similar channels only have 50-75k subs), or a combination of both. I guess time will tell.
Month 1 - 139 total subs
Month 2 - 495 total subs
Month 3 - 1,303 total subs
Month 4 - 2,425 total subs
Month 5 - 3,600 total subs
Month 6 - 4,574 total subs
Current (Month 7) - 5,293 total subs