New account with a $5,000 deposit being made from a non-next day item. How long can funds be held?

I don't believe there is a regulatory limitation, as there are for next-day items, or large deposits, and other hold types. Check your funds availability policy as it should state the holding period set by your bank (it should be something 'reasonable').

Doug's right, it's about what the disclosure you gave at account opening says, not what the regulation says.

New accounts are defined in Reg CC as accounts open less than 30 days. 12 CFR 229.13(a)says that deposits in new accounts are subject the requirements of 229.10(c)(1) parts (i) through (v) and 229.10(c)(2) only with respect to the first $5000 of a non-next-day item. The portion of the deposit greater than $5000 must be made available no later than the ninth business days following the banking day on which the funds are deposited. New account deposits are not subject to the availability requirements of 229.10(c)(1)(vi) and (vii) and 229.12.

However, if your funds availability schedule states shorter hold periods, you need to abide by them.

Actually, that's all about next-day items, which are those addressed in 229.10(c)(1) and (c)(2).
On-us checks can be held without restrictions if deposited to a new account, and non-next-day items (those not covered by section 229.10) can also be held in full.

The bank needs to include in its availability policy disclosure the time period for which the on-us and non-next-day items can be held. That's the number that gets plugged into this portion of the model form C-2 disclosure: "Funds from all other check deposits will be available on the (number) business day after the day of your deposit."