Hi
Looks like you have a lovely routine there
Can I just check - are you happy about moving to formula? If this is something you wanted, that's fine. Just wondering if it was related to increased appetite and you felt you weren't producing enough as this is something you could receive support with?
when do I start reducing the milk intake and adding on solids?
Not for a long time yet. Rather than reducing milk what happens in most cases is that the solids are additional calories so milk doesn't increase but neither does it decrease so just keep going exactly as you are with the 4 day time milk feeds and the dream feed.
Between now and 8 months you could consider dropping the DF so that all calories are taken in the day (BF babies often continue with a NF or DF for longer, this is normal).
At around 10 months or so you might see less interest in one or more of the day time milk feeds. At this point you might swap one of the milk feeds for a solids snack with a drink of water, served at the same time the milk feed was at. This is usually the mid morning or mid afternoon milk.
A little later, maybe 11-12 months you could swap the other day time milk feed and again offer a solids snack with water.
This leaves two good milk feeds per day (usually at WU and BT).
At 12 months guidance is to drop bottles. If you want to continue to BF that's fine. Many people continue with one of the bottle feeds beyond 12 months but ensure that LO is not taking a bottle for long periods as it can effect teeth growth, a quick feed at WU or BT though is not going to be harmful.
Although guidance is to drop bottles at 12 months LOs continue to need either milk or dairy food. Most people continue with at least one good milk drink per day throughout the early years. My 6yo still has a large cup of milk every morning for example.
6 months is a good time to introduce finger foods, so you can serve whatever you are having as a family (taking into account food guidance for babies such as no whole nuts, no honey, low or no salt, no sugar, no raw shellfish) and LO might enjoy eating the same as he sees you eat. Finger foods have all sorts of developmental benefits such as fine motor skill, language development and learning the textures and flavours of the regular family meals.
when and how can I modify the routine so that he has solid dinner later, say at around 7pm? (family has dinner at around 7:30pm, so eventually I'd like him to have dinner with us and not alone beforehand..
TBH this might be difficult for some time yet. LOs tend to eat better earlier in the day so by evening might have no interest in solids at all. Eating earlier in the evening fits more with their natural habit of taking in more calories in the earlier hours of the day, it also allows plenty of time for gas to pass through before BT. Babies don't move a lot so gas can get trapped and be painful if they don't have the chance to get it out before BT. An earlier meal also gives time for any adverse reactions to show up before BT although this aspect you can avoid by offering new foods earlier in the day.
Toddlers are more physically active, obviously, so at that point it might be more comfortable to have a later dinner and not suffer gas pain in the night.
Eating later also relies on a later BT which might not be possible routine-wise for a while unless you chose to move the whole routine on an hour or so making WU, all naps and BT later.
At 12 months I dropped my DS's BT bottle and introduced instead a pre-bath/BT supper. This was in addition to his dinner. So we had dinner at around 4/4.30 I think, then supper (solids snack plus a sippy cup of milk) at around 6 ish followed by bath and BT (with no milk at BT), asleep 7pm. You could also do something like this but with everything an hour later. I would suggest trying it as a supper/snack with the family rather than expecting a large meal to be take at that time.
I hope this helps - let me know if you have any more questions or something isn't clear.