First, many people call any foliar disease of tomatoes "blight" which it may not be
<<<This is late blight
If it is
late blight that you have there is no cure, only prevention and trying to salvage infected plants in my opinion only spreads the problem to the rest of your plants and all your neighbors besides. For actual LATE BLIGHT, It is my opinion that the correct response is to remove the entire plant at once and bag it up to take away and burn. Plants with late blight cannot be salvaged and leaving them in the ground spreads the disease by airborne spores. I sure would appreciate any upwind neighbor of mine to immediately remove and properly dispose of late blight infected plants. Unfortunately, folks don't and that is how and why it spreads like wildfire.
KarenO