Keshe Spaceship Institute has declared every 21st of the month as a day of Peace, starting from 21st June 2015. You can join by signing a Peace Treaty at the Keshe Foundation website.
How about combining the lifework of John Lennon and Yoko Ono with this effort?
Their campaign 'War is Over - If You Want It!' is a perfect match.
I designed a poster to this effect, here in English. This website has some 100 languages.
PDF of the poster below is also available.