Don't make it so complicated. If the CFI is regularly teaching at the school at the airport, then when a prospective student phones in or walks in, the desk person says. "Joe's out flying, will be back in half hour and you can meet him, he has lesson times in the morning at 11." No big deal,
Just to see I phoned my flight school at Boulder, asking about an IPC which I need in 2 months. Friendly guy answers, says Dune is the best one with the simulator and the sim is available most days, and Dune is except off on Mon , Tue. No hassle.
Lets contrast it with Chip 4 who writes under an alias, won't tell us the name of this leading flight school whom students are begging to get into, nor even the airport or town it is located in. So if I was the OP , the student and was thinking about spending not just 12,000 but $21,000 with this guy, I would not only ask other students at the airport, but I'd check out the business name with the Better Business Bureau.
And beware when a guy starts throwing in nonsense like, "I don't work for free" or about a "2 or 3 hour interview", it puts doubt on other things he has to say.