The first and most important rule of the system is only use it for 35 minutes every other day. The time of the day is purely up to you and whether you want to have a foot bath or a full bath is your choice. Either one will benefit you.
The reason for this is that our bodies normally require a minimum of 24 hours to recover from most treatments and any changes and alterations we subject it to. Since we are NOT running at best and optimal, we like to give it a good 48 hours between sessions so your body can have a chance to assimilate and adapt.