"The balance sheet also has Accounts Receivable while the business is on the cash basis. They are using quickbooks."

That's fine. Let's review a few points:

The transition to S Corp would be an "as of this date" event for Balance Sheet. It isn't the same business, so the start up financial data is not "from day 1" of the business. Make sure to understand the Business is not the Entity, but what the entity is doing.

So, if I form my corporation and contribute to it all money in the bank, any debt (such as AP) and AR owed to me by my clients, any office furniture or professional equipment, all of that is "as of" my Corporation starting date, because this is a new entity.

For QuickBooks, that person can provide the Balance Sheet on Cash Basis. And they need some guidance for starting the corporate books properly, and what I describe as "a feedback loop" for how the year ends. Once you work on credits and things like depreciation, you give them those final entries for that year.