I've read a couple of books on tipping points, and it takes between 2-3.5% to reach a tipping point, and create change. With a population of 335 million, that's a top number of about 11-12 million people.
They don't all have to be in the streets protesting. Writing your elected representatives, posting opposition messages online, speaking to, and influencing those around you, even just staying aware and following the news can help.
By next summer, nearly every American will be negatively impacted by Putin's Chaos Strategy that HitlerPig and Skum are implementing as official government policy. Not only will there be enormous protests, but there will be multiple simultaneous protests in every city, representing various issues - inflation, deportations, race relations, women's rights, healthcare, war, etc. Elected officials will be drowning in angry messages from constituents. Even MAGA Morons will be feeling the pinch, and demanding change, and the upcoming mid-term will be looking like a MAGA Republican bloodbath. And it will all be deliberate.
HitlerPig has a very slim lead in both Chambers, and he can't afford a flip in either one, or Dems will have control of investigative committees with subpoena and arrest powers. He cannot take that chance, even with a rigged election. He will have to find an excuse to suspend elections, and time it so it won't make it through the courts before Election day. His frequent criminal and civil cases have made him an expert on manipulating the judicial calendar, slowing it down and speeding it up as needed.
So he will use the time between now and next summer to cause as much chaos and mayhem in the lives of American citizens as possible, creating an historically huge protest movement next summer. Then he will start attacking.
He will encourage his RedHats (the equivalent of Hitler's Brownshirts) to instigate trouble at protests, destroying property, looting, burning, etc., accompanied by shocked and angry responses from official MAGA sources. As we get closer to the election in late-summer, he will start having law enforcement start responding to the violence with heavier violence and arrests of demonstrators, who will be charged with domestic terrorism (for property damage caused by MAGA RedHats), and threatened with deportation to El Salvador without due process.
Finally, sometime in October, he will unleash the military on multiple protests in several major cities, with Tiananmen-style attacks that will kill hundreds, if not thousands. Of course, he will have blamed the liberal protesters for all of the violence every step if the way, and when we are too close to the election for the courts to intervene, he will announce that he is imposing Martial Law, and suspending elections (and protests) until peace can be restored. Since he controls the peace, that will never happen.
Of course, skipping the Mid-term election will soften the citizens up to the idea of skipping the 2028 election, and the he can settle in as Dictator-4-Life, his real ambition.