I haven't had much luck with LED lights. Try a good old fashioned Mini Mag light that holds 2 AA batteries. I have been very successful at picking out pattern morphs such as Cinnys, Pinstripes, and Spiders, and even color morphs like Albino, Hypos and Caramels with one of those lights.
For the OP,
We typically start candling for patterns at day 40. I have founf the earliest that I can confidently say what is in the egg is at about day 48. In my experience, that pattern does start coming in at about day 32, however, it is developing and will change as it ages a bit more. If you happen to have an egg die in the 30-38 day range, you will see that the pattern has not fully developed yet. Around day 48-52, I have found that most of the pattern is fully established, and the color starts coming in. I have seen the color take as long as to the day 59 point to fully come in.
I hope that helps,