Depending on how well you build and maintain the pile, it could take from several weeks to a few months. The pile smells bad. Too much moisture. Turn the pile. The pile will not heat up.
Pile size is too small.
Lack of nitrogen-rich material. Particle size too big. Collect more materials and rebuild the pile to at least 3' x '3 x 3'. Mix in fresh grass clippings or kitchen waste. Chop or grind materials.