It depends on what you want. The milky trichomes have the most THC (euphoric) and terpenes since they are ripe, the amber ones are overripe and contain more CBD (narcotic), and the clear ones are not ripe yet. So you have to decide how you want your high to be. I always harvest when it's about 80% milky and 15-20% amber. Of course, you will still find clear ones, but that's roughly it. And I would check the trichomes on the flower calyxes and not on the sugar leaves. They ripen faster on the sugar leaves, so look at the calyxes in the buds and also check the ones a bit further down to make sure most of the flowers are ready. I hope this helps you a bit in making your decision.