Read the report.
From the Introduction in the Mueller report, page 9 paragraph 3 of the report....
" In late July 2016, soon after WikiLeaks’s first release of stolen documents, a foreign
government contacted the FBI about a May 2016 encounter with Trump Campaign foreign policy advisor George Papadopoulos. Papadopoulos had suggested to a representative of that foreign government that the Trump Campaign had received indications from the Russian government that it could assist the Campaign through the anonymous release of information damaging to Democratic presidential candidate Hillary Clinton.
That information prompted the FBI on July 31, 2016, to open an investigation into whether individuals associated with the Trump Campaign were coordinating with the Russian government in its interference activities."vs
Strzok to Lisa Page on July 28 about their
open investigation , which would be 3 days before July 31 on my calendar ...

Lol