A deal for the Inter Milan midfielder couldn't be done in time last week.
Di Francesco said, “I am not angry that Nainggolan didn't arrive, there were various situations that caused it.
“We must not look back, but forward with confidence. It's an extra-large squad I have many players at my disposal and we need to make sure everyone gets their fair share.
“The break for international duty was very helpful, as it allowed me to work closer with certain players like Filip Bradaric and Luca Ceppitelli. I asked them to make it difficult for me to choose my starting XI by raising their game in training.
“Balance is important, then when we get more confident and pick up points, we can use a more attacking approach.
“The crucial element is for everyone to sacrifice themselves in helping the defence, that is what the players must understand."