To preface this, chicken and human rigor mortis is roughly the same. For a chicken if you slaughter the chicken and want to eat it, you have less than 1 hour to get the chicken in the pot before rigor mortis, else you have to wait 8hours. The normal amount of time recommended is 3-5 days in the fridge to let the body relax. For humans it's 2 hours till rigor mortis then 8 hours and most likely another 12 hours of rigor mortis.