Who to sell to?

Selling my old bike. Person 1 sends an email reply to my ad, and then we agree on a price and I ask when they'd like to pick it up. No response. Then person 2 emails me, agrees on price and schedules to pick it up on Tuesday morning. Then, Person 1 finally responds (a whole day later) asking to pick it up tomorrow. Who do I sell to? And what do I tell the other person?