In my airline the SOP for CDA is to fly it on automatics, set the MCP ALT to the MDA rounded up to the nearest hundred feet, not to get extra margin but since you only can set the MCP ALT in hundreds. Hence the MDA is not busted and the desicion is made already on the ALT ACQ (737NG) mode change. If not visual then, wait for the ALT HLD and then execute the go-around. Obviously this has the effect that some approaches could have lead to successful landings instead of G/As, when the weather is right down to the minima. Not saying this is the way to do it, just saying they way it is done...