24 months is measured from bonus posting, rather than from account opening or closing.
Really? Interesting... so I guess OP does not need step 2.5 and 5.5 if both wife and husband CSP are over 24 months old since last bonus posted.
Personally I would just open up 2 CSRs and get the 200,000 UR points bonus instead and then transfer the CSPs points to CSRs and close CSPs. Oh wait.. that's exactly what I did!