In soil and coco, generally you'd want to use a week's worth over 5 - 7 days. Try to get in at least 3 waterings during this time. Some growers water every day - others water every 3 days. If watering every day, I typically tell people to use it for 5 days, then have a nice 10 day flush!
In hydroponic systems, Winter Frost works fast! Rockwool, clay pebbles, perlite and sand hold very little plant nutrient. Rockwool has been known to show effects in as little as 24-72 hours! So go easy and use it for a couple of days at most to begin with. You can always be more aggressive in the future. Just be aware that if you use Winter Frost for a Full Week in these substrates, there can be deleterious effects on plants.