Hi and welcome to the forums
Do you keep the nap at the same time everyday irrelevant of his EW? It would be good to see how the last few days easy have gone if that's ok? It's great to see what you're striving for, but the good stuff is usually in the finer details
So has he always managed 12hr nights if you do the earlier BT? When did he drop the CN if I may ask? And how long has he been on the current routine? Sorry for all the questions, it just helps with trying to see the full picture.
Normally EW is a sign that the morning nap needs to be moved later and/or teething. If he's been on the same A time for a while, that might just need tweaking slightly. Difficult I know Shane their waking early, but it is doable. I've btdt!
Has his milk intake dropped recently since moving to 3 solid meals? I would monitor that as milk is the main source of nutrition until they're one and is much more calorie dense than solids. That being said, it doesn't sound like that's the main issue. Is he bf or ff? And DF or nf except the 6am one?
At 7mo I would expect the A time to be closer to 3hrs than 2.5 as your working to. Perhaps just pushing out that first A by 15mins, holding for 3 days might help? It may need an increase again especially as he's not a fan of a longer A to BT like mine
. I personally wouldn't offer a CN as it might be that his sleep needs have dropped and then you end up with a stupid o'clock wu. All in all he is getting a decent amount of sleep in 24 (even with the EW) it just needs adjusting a bit xx