For a start, I gave my son cerelac twice a day. For portion wise, it's a trial and error. Some babies eat more, some less. You may want to follow the guidelines given on the box. By 8 or 9 months, I moved on to porridge. The easiest way to cook porridge is using a slow cooker. It takes more than 2 hours to cook but vegetables or meat will be very soft so easier for babies to chew and swallow. If you want to use your normal rice cooker, I think it's ok but meat and vegetables might not be soft so you might need to blend the food. How long babies eat porridge really depends on your baby's interest. My 14-month son still enjoys eating porridge. And I do give him snacks like baby biscuits or fruits in between meals.