Prompto might have made a comment about how getting caught up in logistics meant maybe Nina'd been talking to Iggy too much lately, but he was still a little caught on the first part.

"April?" he gawked at Nina slightly. "That's, like, ages from now, Nina!"

Though, he will admit, telling him about it now was good, because that gave him a chance to actually think about it, then maybe forget about it, and then think about it again fresh when she reminded him.