Colorado was invited right away, because they were part of the Texas move and the backup plan - so in regardless of the next move. Utah wasn't invited until after the Texas move halted.
I believe that the B12 will make sure that a deal is worked out for BYU and #12 (Cincinnati or Houston?) before they officially invite #13 and #14. If BYU is in, then Colorado St. may be an option, but there is no way that the Big 12 goes after CSU without BYU in the fold. Likewise, if it doesn't work out with BYU, the B12 may decide that they need UConn or UCF/USF tandem to make up the difference in what they would have had with BYU.