if those big fan leaves go yellow you drop into a N lack. That's a classic "usecase" of watching the lower fans - happy to have them still imo. They will provide whats needed as long as they are there and are great indicators of what you are experiencing. And it fits to what you tell. If you were a little too early things should even out, as N need drops. The yellowing will stop as you keep feeding as normal/intended now.
Just keep those lowers/big fans and let them provide what they still have until the N lack comes to rest.
Just keep those lowers/big fans and let them provide what they still have until the N lack comes to rest.