Genetic sex testing kits let you identify males from a leaf punch at about a week old, long before preflowers appear. You send a tiny sample to a lab or use a home kit, and the result comes back within a few days, which frees up space and lights weeks earlier than visual sexing. Costs and turnaround times for the main testing services are listed side by side on https://breederregularseeds.com, and the home kits looked noticeably less accurate there. For small personal runs I still just wait and look.