Tank Repair how long to let GE Silicone 1 to cure

[cdnco2004]

I broke my overflow box on one of my tanks and need to replace it to keep the livestock from going down the drain. All the tank work I have done before was while it was empty before water and fish. I figured I will lower the water level low enough that I can put the new overflow box on but how long do I need to keep the water level low to let the GE Silicone 1 to cure before rising the water back up to normal?

 

[CrayHawk]

I let mine cure for a week. I put baffles in the sump, so that may have more pressure against it.