The illinois Legal Malpractice Blog writes about the statute of limitations:

"A recent Illinois Appellate decision (Warnock v. Karm Winand & Patterson) stemming from a failed real estate sale addresses the issue of when the two-year statute of limitations begins to run in a legal malpractice case – is it 1) when the underlying action is first filed and the client is put on notice that his attorney(s) may have been negligent or 2) when a decision is rendered in the underlying action resulting in a monetary loss for the client due to the lawyer’s negligence. In it’s decision the Appellate Court found that in the majority of legal malpractice cases the answer is the latter, saying "in Illinois, a ’cause of action for legal malpractice will rarely accrue prior to the entry of an adverse judgment, settlement, or dismissal of the underlying action in which the plaintiff has become entangled due to the purportedly negligent advice of his attorney.’" (citations omitted). The Court further stated, "[t]he existence of actual damage…is essential to a viable cause of action for legal malpractice."