Get it as cold as you can for at least a day or more, obviously without freezing it. I usually do it after primary ferment is done 10 days or so. If I am dry hopping in the fermenter then that gets done before cold crashing. I mostly keg, but the few bottles I do with the leftover beer carb up just fine. By the time I'm done transferring the 5 gallons into the keg, the leftover few bottles of beer have warmed up into the 40's and I drop a Coopers carbonation tablet into the bottles and seal them up.
I suppose if you left it cold crashing for too long, then all the yeast would eventually fall out and you'd have trouble carbing, but a few days is not an issue.
Make sure to plan for the temperature change by not having a bucket of liquid with a blow off tube hooked up or you might wind up with all that liquid sucked back into your fermenter. I use a piece of open cell foam instead of air lock, but others report that the S type of airlock does not allow suck back into the fermenter.