Yeah, I think this is a common issue. My advice is start planning earlier. When I reach out to inquire about a session. I usually give it about 48 hours to get a response. After that I'll send an email explaining that since I haven't heard back I'm going to continue my search and I wish them my best. You'd be amazed how often I get a reply 5 minutes after that. But even if I don't get a reply, I can feel I'm moving on with full transparency.

So imagine that you might need to send inquiries to 3-4 Dommes before something works out, so ideally you would start at least two weeks before the date.