Hairs are just now turning amber,11 weeks into flowering, when to start flushing?

My plants are 1/2 indica and 1/2 sativa. I'm not sure when to start flushing at this point. Hairs are light to medium brown. Trich's not turning yet. So when do I need to start flushing and roughly how long a period from when hairs start to turn until they turn red?

Start flushing in about a week I'd say judging by how old they are already...

ok thanks for your help