Believe there are diff opinions on when to start solids. Some says that as long as baby shows interest and able to sit upright and strong neck, can start to introduce. On the other hand, some firmly believe only to start at 6 months onwards. Guess you can follow ur own motherly intincts. No harm introducing solids once a day, just a couple of spoons for ur baby to explore textures and tastes, but milk still is the primary source of food for them.
My LO is 4 months old and pd recommends to let her try not more than 1 teaspoon. Informed the nurse at polyclinic during vaccination, and they did mentioned that she is sitting well on her own (sit up straight while holding onto one of the hand). If you want, can go ahead with small quantity to just slowly introduce food to your baby.
Can check with pd