Billing Service Contracts in Advance of Service Dates

I am reposting a question that someone posted in 2014, as the responses solved part of their question, but never answered the question about:
"Working with Field Service Contract Entry and AR Contract Billing. We typically bill our customers 1 month in advance. That way if they don’t pay we don’t show up. Epicor seems to be set up to bill for services rendered and will only generate an invoice after we have already been there. Does anyone know of a way to set up Contract Billing so I can bill out a month in advance? "

I would like to know how to generate an invoice for an Service contract period in advance of the period.