First Wonderwoman Greenhouse Grow

Odd week figuring out all the bits that didnt go so well for the next one. Have now built my own box which il use to raise seedlings in until theyre ready to go outside with plenty of lights. These ones didnt get enough light their first couple weeks so hopefully that improves for next time. Day 20 I moved the containers to a windowsill whilst I built the box and it was such a hot day that after feeding them in the morning the pot was light at the end of the day and as they were in a black pot I think the roots mightve been stressed? I gave them a couple days and seemed to be a bit more stable and transplanted yesterday into their final pots. (Gave soil a little water, michorrazea and then transplanted in) using Canna Terra Professional + soil and was about to start the nutes but realised they are now in nutrient rich soil would it not be too much if I gave nutes now? Thinking il wait another week before adding them but let me know what you think. Thanks!