How Long Should You Use and Test a Product Before Using It?

How long should we use and test a product before we really you know determine if it's not working for us or if it is like how long should we test it well it depends on the product. I always believe in double cleansing anyway we were demological invented that whole thing we invented at the International Dermal Institute before Dermalogica which is where you cleanse without usually an oil based or a cream based cleanser to remove those pigments. You're going to know right away if it stings your eyes return it, some things are more subtle such as sunblock or moisturizer. If after six weeks you're not feeling that you're loving this product I would take it