Your question is a bit tricky. I am assuming that the number you intended to type was 100,000 and not 1,000,000!
Assuming that is correct then probate may not be required assuming everything is good with those inheriting the funds. If not, then probate may be necessary. As far as the period to contest a Will, according to the Illinois Probate Act you have six months to file a Petition to Contest the Will after it is "admitted to probate." However, if the Will is not being probated then the situation is likely covered by the statute of limitations which is two years from the date of the decedent's death.
However, I would like to note that waiting might be a bad idea in many instances, since when the money is gone it may be really hard to recover. Thus, if you have questions on how to proceed it is wise to consult with a local probate attorney ASAP.
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Let's work backwards --
While other states require and limit the time period in which a will may be filed following a testator's death, Illinois does not. Instead, Illinois requires anyone in possession of the testator's will to immediately file it upon the death of the testator. Relatedly, if the executor is aware they are in fact the executor of the will, there is a statutory duty to present the will for probate or declare his/her refusal to act.
Note though, situations do occur where the will is not found or known until years later. For instance, a widow presented a will for probate 8 years after the testator's death. The widow was acting in good faith and hadn't been concealing the will. She simply wasn't aware of the will.
Next, it is important to understand the authority of a court to hear a will contest. The six-month period is best viewed as a jurisdictional limitation and not a statute of limitations. This difference is important for issues of "tolling." Thus, if a will contest is not brought within six months of the will's admission, the court is without jurisdiction to hear the contest.
In short, go see a probate attorney. Springfield is full of them. Just because a small estate may be handled via a "small estate affidavit" does not mean it should be. Especially in cases of dispute and contention.
While a person has two years to contest an unprobated will, acting quickly is critical. Money disappears faster than anything I've ever seen, particularly when it's someone else's. Get to a probate lawyer now and talk about your rights and what it will cost to protect them.
Please be sure to mark the best answer to your question. My answers are general and do not form an attorney-client relationship. I'm happy to talk to prospective clients in my areas of concentration and geographical location.