Deposit for multi visit job

Customer has paid up front for the mowing season. I am thinking in terms of scaling and someone other than me doing the billing. 

How do i record the deposit and all future visits (they are invoiced per visit) when invoiced show that they have been pre paid. Im not sure if im explaining this properly. I understand when a quote is made and a deposit is made the the next invoice tracksthat... but not sure how to do that from this point. Especially when someone else gets involved or too many customers. They wont "just know" thats its been paid if that makes sense.