My recommendation would be to start with "soft" consumption. Most first timers eyes are bigger than their stomachs. You may fantasize about a beautiful Mistress dropping her load into your hungry mouth. The truth is, shit eating is an art form. To be a good toilet slave requires practice and dedication. A good feeder understands this and will bring you along slowly.

Start with used toilet paper licking, or light consumption from a plate or bowl. This advice may not play to your fantasy, but it will save you from a shitty experience.