Bank gave customer $500 next day from a large deposit, so for the next $4,800 available 2nd business day, do we still hold $4,800 or do we hold $4,500 until the 2nd business day (for a total of $5,000 - between next business day and 2nd business day funds)?

I would do the hold for $4,500.

I would agree with Timeline- Hold $4,500 for 2 days and the remainder as a Large Deposit hold to maximize the amount held under the longer hold.