This is a very difficult question to answer as everyone's skin is different and it also depends on the severity of your eczema. Also bare in mind that Dry Eye Gel is not a medication, and so it has to work in harmony with your skin's natural pace.
However most people tend to see an improvement in 2-3 weeks, though if your eczema is very severe this may take longer. You should also make sure that you are not using any other products around your eyes that may aggravate them, in particular make up removers, cleansers that contain chemicals or eye make up that contains glitter or very bright colours. Waterproof mascara can also be an irritant and is also problematic to remove as requires harsh cleansing or make up removers that contain detergents to dissolve the mascara.
In addition many chemical sun creams can also irritate the skin around the eyes if its prone to eczema, as can concealers containing SPF's. It's best to use pure mineral SPF's and mineral based concealers.