I heard Sarah Carter say the other night that if there were criminal referrals, that it would slow down the release of the IG report. That makes sense.
My guess is that of the 5 issues being investigated, we'll see reports on maybe 3-4 soon. I believe the first issue, which involves Comey's July 2016 statement, and the Oct 2016 letters will take the longest to investigate. See the IG announcement of the investigation. Note the last sentence in particular.
https:// oig.justice.gov/press/2017/2017-01-12.pdf