I take dogs from multiple clients pretty much every week but if I get multiple requests that pushes me over my limit (5 boarders) than I always book return clients to be sure they continue using me. If all the requests are from New clients then it's a first come first serve basis.

I always ask clients to bring food, dishes, leash, and a bed or crate depending on where they normally sleep. I tell them they can bring anything else they want but discourage toys because other dogs could destroy them. I have a stockpile of toys plus extra dishes, leashes, beds and crates in case something is forgotten. ( bowls are surprisingly forgotten quite often!)