How to cook baby’s porridge

Im a ftm, ive never cooked porridge before. And would like to know in advanced how and when to cook baby’s porridge. At which month did you introduce porridge to your baby? How do you make baby’s porridge? Or specifically which device/cooker do you use ? Do you use specifically for baby or just use normal rice cooker? And usually how much/ how many portion did you cook and how long does it take? Can give me links if you have any! Sorry for the lots of questions as im still new and clueless. Thank you so much!