Just try to keep your EC in the middle of the road, for all stages of plant growth. When they get bigger, you'll either feed more often, or in larger quantities, if you up-pot. But the ratio should not just be changed for the sake of trying to do "more-better-er". If you up the EC, know why you're doing it. Personally, I always err on the conservative side. If for no other reason, because I don't like flushing out media. It's a waste of money, if you're just building up salts in your containers.