Depends on the type of plant, number of plant and also on the grower. My first grow never smelled even at budding. However my new buds started smelling 3 weeks into veg and now 10 days into flowering stink. There are many methods depending on the grow. Could use a carbon filter for larger grows. Smaller grows which is what i am used to can be masked with ionizers, different air fresheners that release periodically. Could also try kitty litter inside the grow environment.