@Vickie89 How did anyone know you'd be a safe host when you first listed and had no reviews? It sort of goes both ways. Are you using Instant Book or is this a Request? If IB, he must have verified ID if you require that and a proper profile photo. Has he bothered to fill out any profile info? Communication is key. What kind of message did he send, if any? Write to him, ask some questions. Nothing wrong with saying "Hi XX, I see you are new to Airbnb, so since you don't have any reviews yet, just want to make sure you've throroughly read through all my listing info, house rules, etc, and are clear on what you are asking to book and willing to adhere to our house rules. Also, make sure you are booking for the correct number of people you will have in your party, as guests not mentioned on the booking will not be admitted." That sort of thing.
I've accepted several guests who had no reviews, and they turned out to be fine. I really go by how they communicate, and whether they respond in a timely fashion.