ACH payments; When is hold initiated / Customer sees pending transaction

Hello all, I contacted Quickbooks support via phone & chat but could not gather a clear answer. My first few "deposits" (ACH pulls) each have a deposit expected date 5 days from when the transaction was initiated. On the phone a representative told me that though my account has been cleared for next day ACH deposits, I could expect deposit times of five days due to the size of the transactions, ($10,000-$15,000)

When the transaction is first processed, an expected deposit date of around 5 days later is given to me. It also says, "you were paid! your money is on its way". My question is: What does this mean? Has the transaction/pull been sent to the customers bank? Have they began reviewing it? Has the customer's bank placed a hold on this amount of money? Does the customer see a Pending transaction at this point?

If not, then at what time after initiating the transaction, and before the money is deposited to my account, does the customer's bank receive the pull, place a hold on the money, and the customer see a pending transaction for the amount pulled?

Thanks!