When I defol I usually do a heavy one right before the flip to flower and 2-3 weeks after the flip. I remove any leaves blocking light from reaching deeper into the plant or ones that block airflow. I also tend to strip growth off the bottom 1/3rd of my plants as that usually doesn't grow into anything worthwhile. After the last big defol I will take a few leaves here and there to keep light reaching deep but I don't go crazy with it. Your plant, however, is quite small and lanky. You probably don't even need to bother with doing defoliation right now. just bend the branches to open the plant up and allow more light to the lower parts.