5
Hire three people, in this order
A lawyer, a CPA, and a fee-only fiduciary adviser. Not a friend of a friend.
The lawyer goes first, because they set up whatever entity you claim through and everything else depends on it. You want someone who does trusts and estates, and ideally has handled a sudden-wealth client before.
The CPA goes second, because the tax bill is the largest single item and the timing decisions are theirs. A jackpot is taxed as ordinary income and the top federal bracket applies to nearly all of it; the 24% withheld at source is not the bill, it is a deposit against it.
The adviser goes third, and the two words that matter are fee-only and fiduciary. Fee-only means they are paid by you rather than by commission on what they sell you. Fiduciary means they are legally obliged to act in your interest. An adviser who is neither is a salesperson with a good title.
Interview more than one of each, ask directly how they are paid, and be extremely wary of anyone who arrives as a package, a lawyer, an accountant and an adviser who all work together and all found you at once is a structure with no independent check in it.