Great idea!!! From now until the 6th that is what this sight needs to be about!! Where to be, who will be there, what to bring, where to meet and so on!! It's time to rock this mother fucker!!!

Singles and small groups have their own problems, but one large group in one area can be bottled-necked and bottled up. (Look up Kettling @ https://en.wikipedia.org/wiki/Kettling or another source. ) D.C. Police used kettling in 2017 at Trumps first inauguration so they know how to do it.

Many smaller meeting points that converge into common locations may work better. The larger groups would be on the move harder to stop.

There needs to be multiple routes, including split/rejoin. Scouts with walkie talkies ahead of a larger group can relay information backwards. Have a channel plan with fallback. Using the security they provide is more "Selective Calling" - it doesn't stop anyone else from listening with scanner. Cell phones should work, but could become congested or have other 'technical' problems.

Failing all that, use American Flags to visually signal a few city blocks away -- worked in the 1860's and earlier. Point it where you want people to go, not where you don't want them. Don't point it "Oh look there is something interesting here" Need several per group so the front holds at the turn location, then directs the group past, and then returns to the rear and works their way back up, or joins the group behind if that's the way it goes.

There is no perfect way to do this. Public plans can be worked by any opposition and plans not public don't allow for coordination.

There’s no age limit on defending your country

https://en.m.wikipedia.org/wiki/Samuel_Whittemore#:~:text=Samuel%20Whittemore%20%28July%2027%2C%201696%20–%20February%202%2C,colonial%20combatant%20in%20the%20American%20Revolutionary%20War%20%281775–83%29.