The Washington Post is saying September:

The planning, which has not been previously disclosed, involves several options, including mobilizing at least a few thousand members of the National Guard as soon as September to what is the third most populous city in the United States.

The mission, if approved, would have parallels to the polarizing and legally contested operation that Trump ordered in Los Angeles in June, when he deployed 4,000 members of the California National Guard and 700 active-duty Marines despite the protests of state and local leaders. The use of thousands of active-duty troops in Chicago also has been discussed but is considered less likely at this time, said two officials who, like others interviewed, spoke on the condition of anonymity because of the sensitivity of the issue.