I use the circular filters and look out a window - nothing exceptionally bright anymore. I am usually sitting away from the window close to ten feet.

The colored filters are only big enough for one eye, so I hold it over one eye and then cover the other one. After I feel my brain has had enough, I switch. I only do syntonics on occasion. And it's usually less than a minute on each eye. If I do it consecutive days, sometimes I feel I only need a few seconds, and sometimes I put it up and my visual system doesn't want any, so I stop.