Hi
Unless there's a family history of allergies or he has any other health issue there isn't really any reason to hold back on solids at all. You know many of us have gone the baby led weaning route where baby self feeds all sorts of foods right from 6 months. Maybe you'd like to look into it. It means you can prepare regular family meals (minus salt, sugar, honey, maybe cool off on the hot spices a little) and just pop a bit in front of LO whilst you have yours. It's great for fine motor development and apparently speech development too.
If you prefer to go the traditional puree route you can still introduce a wide range of solids, much of the waiting-3-days-thing was related to when babies started purees at a much younger age and it isn't considered necessary if you wait until 6 months. In the UK finger foods are advised to be introduced alongside puree after only a week or two (so still at 6 months), and to rapidly move from puree to mashed to chunks in a very short time (again the many months of purees dates back to previous generations when solids started younger) so that baby joins in family meals as soon as possible. In fact many areas of the UK the health advisors are now recommending the BLW route instead.
I would give milk feeds at the regular time, and the full amount then offer solids an hour later. Offer until he refuses (turns head away, throws or drops food, pushes it away, refuses to open mouth etc) and don't try to coax another mouthful so he can respond to his own full signals (if you offer finger foods he will just stop self feeding or will push the food away). Don't forget a sippy cup of water alongside (I used a bottle of water too in the very early days when my LO was thirsty but couldn't quite handle the cup). The only time you would need to watch the quantity is if his milk intake drops too low. Milk should stay the same amount at this point and solid foods are for tasting and experience and to 'add on to' the milk feed, not to take away from the milk feed.
Rice cereal, it doesn't have much in the way of nutritional value, I would skip it tbh. If he is wincing with every mouthful perhaps he'd prefer a bit of mashed carrot or some steamed carrot batons? Or some baked pear/apple wedges? or just a bit of something you are serving yourself?
Don't know about refusing the DF. Not heard that one before. Might have been a one off.
hope this helps
