I don't see why you couldn't do this whenever, if the estate really does owe you money and the executrix isn't paying. One of the biggest duties the executor(-rix) has is to pay off the enforceable debts of the estate.
Unless there's some wacky chauvinist common law rule against suing the executrix (say, you can't because she's a woman, and women are weak, insert other misogynist bullsh!t here), I can't see why you wouldn't be able to sue her to make her pay the estate's debts owed you.
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