If you're planning to keep them in the small cups they will need nutrients eventually. But if you're planning to transplant them, and into nutrient rich soil you may not need to actually feed them for an additional 14+ days after their transplant. However if you do feed them in the small containers I'd definitely be at the 1/4 strength...at least until their reaction is seen. For me personally I never had to feed my seedlings until they had already established decent roots and were ready to transplant, so really it may have been around week 4 depending on how quickly they made it to 3gallon+ pots. I think if they remain healthy green and growing at a good rate you may not need to either with photoperiod plants. ✌️