All effects of Glistening Deluge are determined as it resolves. Creatures that enter the battlefield later in the turn won’t get -1/-1 or -3/-3, nor will noncreature permanents that become creatures. A creature that gets -1/-1 won’t get an additional -2/-2 if it later becomes green and/or white. A green and/or white creature that gets -3/-3 won’t have the -2/-2 rescinded if it later stops being green and white.