Yes, can someone please answer this question.

If it's 28 coins per block, then 1.6 million would be mined at about block 57142.  We're at about 49600 right now, leaving a difference of about 7542 blocks.  At 1.75 mins per block that would take 220 hours.

I don't want to mine after the 1.6 million are exchanged as the CAI coins will be worthless, but how do we know what block to stop? 

Also, is the ~32k CAIx on coin swap the last that will be exchanged?