Thanks, CCA. So just putting a lower MCP altitude (6,000' in this case) isn't enough. You have to install an approach and put the first fix in 1L for it to descend. I think it would descend anyway in that case as soon as you rolled in 6,000 and altitude intervened. (Inserting an approach fix in 1L puts it into CRZ and altitude intervention puts it into DES.)
Mustafagander:
I am aware that the option of using a non-VNAV mode (FLCH, VS) to descend while in CLB mode would be an alternative and probably preferred method, but I'm interested in whether DES NOW would force it into DES while still in CLB.