Yes your yield will be lower if you harvest when cloudy. In my experience it usually takes about a week to go from mostly cloudy to a decent amount of amber, and in a weeks time your plants will certainly pack on some weight. People who are growing outdoors for profit usually weight as long as they can to get the most weight. That's one of the reason Mexican brick weed is brown. It's over ripe. If your going for a balance between yield and quality, harvest at about 10% amber.