I started with purees (apple, pear, banana, carrot, prune, etc) and baby cereal. Started with maybe 2 baby spoon’s amount, 1 time a day. Then gradually increased the amount and number of feeds per day. The milk intake can drastically decrease in some babies because food is a lot more exciting. So I made my baby drink milk first before feeding solids (half an hour in between to digest). I didn’t go see a PD. As long as baby has sufficiently good head control, can sit in the high chair (buckled up), shows and interest in your food and is willing to take the spoon, I think you can start.
https://community.theasianparent.com/q/first-food-i-gave-babyi-started-when-5-month-oldi-started-with-1-sc/1682976?d=android&ct=q&share=true Hope it helps!