...Because that's how long it takes the coup members to replace all administrative & authority roles with their own loyal people. When they go from couping the government to BEING the government.
We must organize & mobilize by, say, mid-summer to stand our best odds of taking our country back. To go much longer pushes us into risking encroach a borderline insurgency resistance. Which can go on for DECADES. Literally. Look at Ireland's example. Or Sri Lanka.