Recommended time is 10-15 mins depending on the skin stain and result required.
If a lighter result is required then 5 minutes can be a suitable time for many clients. If tinting after brow lamination colours generally process faster due to higher hair porosity after chemical services, 5 mins is a good recommended time for after brow lamination. Always monitor colours while processing, you can always remove and reapply layers if a darker colour is required.