Yup! Part 3 of the post explains why there is the lag:

http://engineering.zenpayroll.com/how-ach-works-a-developer-...

By the way, I hope no one minds if I insert a plug here: We're working on some very interesting ways to cut down this time in our engineering team and we're hiring on all fronts. Shoot me an email directly (in my HN profile) if you're interested in learning more!