Although our kids are roughly the same age and have similar issues we are a bit further down the road than you so I can give you a few ideas of things that have helped us.
1. Support the strengths outside of school. 1 grade level ahead isn't going to even scratch the surface of what your DS probably needs in some areas. My DD's strengths are in comprehension areas (and she has been diagnosed with just about every LD there is) so we have done a ton of high level audio books outside of school, starting before kindergarten. The summer between 1st and 2nd grade a neuropsych included in his report that she HAS to have high level audio books. She needs them like she needs air. (Well almost...) So based on that we had 2 daily enrichment/anxiety breaks written into her IEP for 2nd grade where she got to listen to books of her choosing. When she transferred to an out of district placement she was placed in the 8th grade reading comprehension group as a 3rd grader. She still found the pace to be "painfully slow" but enjoyed it. The teachers couldn't really wrap their heads around this little kid needing such high level material so it's a work in progress. But get him that enrichment however you need to do it. (A friend with a 2E kid who is PG in math has had him working with a tutor for a couple of years to get in what he needs outside of school. As a 4th grader he has been attending honors algebra at the middle school but by next year he will probably be needing 12th grade level math. This kind of thing has to be individualized - no 2 kids will be alike.)
2. Support the areas of challenge by assuring he has access to all the services and accommodations he needs. I saw your post about the teacher's behavior during your IEP meeting. A number of us here have had a hard time getting consistent implementation of the IEP by classroom teachers who don't get it. I think probably all or at least most have heard our kids called "lazy" in those situations. I recommend watching that teacher like a hawk. Hopefully the supporters from your meeting will continue as allies. Don't look for trouble where it may not exist but be ready to react immediately if he doesn't get the support he needs. I chose to hold my district accountable to provide whatever services DD needs but other parents choose to hire their own therapy team outside of school. There are pros and cons to each approach...
3. Emotionally and socially my DD has benefitted from 2 things - a) having close friends who have known her for years and get that both the strengths and the challenges are intrinsic to who she is as a person and b) participating in a musical theater group that provides regular, consistent access to neurotypical peers of a broad age range. Her current show has a cast ranging in age from 6 to 17. During the summers she does shows with casts that range from 4 to adult. This means she has gotten comfortable being around people of all ages and abilities so her asynchrony doesn't just apply to a backdrop of same age peers. She may sit and play Barbies with a group of little girls, talk about character development with a group of teenagers or discuss her experiences with an adult who also grew up with LD's but didn't get the kind of support DD is receiving.
4. We got very lucky and found an amazing psych who is both 2E herself and the parent of a 2E child. She has been an incredible resource both helping DD accept herself and working with the schools to get them to understand her rather unusual circumstances.
5. Use this board to help you navigate the process. There will be times you want to scream or cry or punch someone in the face. There will also be times that you are bursting with excitement or pride over things no one in real life could possibly understand. My 9 year old can finally tie her shoes or wore her first pair of regular pants (with a snap,and a zipper). Parents here with dysgraphic kids will get it and share your excitement. That same kid question how King Lear could possibly be considered a tragic hero? Parents here will say "We had that very same conversation the summer my DC was 10..."
6. Cut yourself some slack. You will spend a crazy amount of time figuring out what he needs and how best to get it for him. Give yourself room to breathe as you work through it all. You will probably hit some walls as you advocate but you will also have some significant triumphs. Don't forget to let yourself enjoy the good times.
Hope this helps.
