Yes. In fact, probably back in 2000, or even earlier.
The plan to steal elections occurred in the aftermath of the Bush v Gore election when Soros, an the rest of the world, that it was the Secretary of State that held election certification power. He then started the movement to get demoncrap elected SoS instituted in each state. It was also at this time when computerized voting was in its infancy. People called for computerized voting after the hanging chads were a problem. Armed with the knowledge of computerization being called for and SoS power to certify the results this became the catalyst in which the left started to hatch the plan we saw in the the November 2020 election. Each election held was a test for the next.
As far as mail in voting was concerned, the call for mail-in voting has been talked about since before the election of 2000. The derailment came when people could do early voting and the advent of computerized voting. When ballot harvesting started popping up, mail in voting started to be whispered around the country. The State of Washington implemented mail-in voting in 1971 but it became law in 2005. In 2003 Motor Voter became law and in 2002 the states were required by the Federal Government to replace card punch lever voting machines.
The previous laws and changes leading up to the 2020 election all became part of the plan to steal the election. It was interesting that most MSM, including FOX, Newsmax and OAN, called mail-in ballots, absentee ballots. Something that a lot of people also started calling the general mail-in ballot.