Starting rice cereal

So my little one will be 4 months in two days and the past week he has been downing 8oz now of milk and seems not to be getting full. Dr said at his 4 month check up she was going to go over rice cereal with us. That apt is in a week and half I kinda want to just go ahead and get started on it now. I'm not going to put it in his bottle I will be spoon feeding him. When did y'alls start rice cereal and at time of the day did y'all feed it to them?