The 21st Annual Greenwich Village Children’s Halloween Parade precedes the big one which starts at 7 p.m.! and winds its way around Washington Square Park this afternoon. Children and families gather at 3 p.m. at the Arch. Hosted by Community Board 2 and N.Y.U., the parade starts marching at 3:30 p.m. It will make its way to LaGuardia Place between Washington Square South and West 3rd Street where there will be candy, rides, face painting, music and other entertainment. This goes until 6 p.m.