I'm nd and so is my son. You need to find what works for your son not what works for you. We did a lot of reading- It's an autism thing I'll help you understand Emma Dalmayne really helped. Also on face book - ask the autistic adults which is a page where nd adults support parents of nd children. (Obvs these helped for our son as he is autistic)
Look at what your child needs are they sensory seeking or avoiding-
Seekers will need extra stimulation such a fidget spinners sensory toys etc they may get overload though so ear defenders can help.
Avoiders disliked noise stimulation so ear defenders, avoiding busy/loud/bright/crowded places can help.
Some children can be both in different ways so it's finding what works for your child.
If your child has stims - echolia, head shaking, flapping etc don't inhibit as these are stress releases unless it's dangerous such as banging head then work towards swapping for a more positive one.
Communicate with your child in a way that works for them, it could be spoken, pictures, sign language. Understand your child's brain doesn't work work the way yours does so don't expect them to respond typically. My son often parrots back this is not conversation in the was nt people understand it. So if I say "turn tv off" he may repeat "turn tv off" but he isn't saying he will turn tv off nor is he agreeing to tv going off if that makes sense.
If they like routine/advance warning have a daily planner. Talk or show pictures for new things that are happening to prepare them.
Don't punish meltdowns it's not a bad behaviour it's the child becoming overwhelmed by their environment which is down to you.
If your child has meltdowns look at what causes them - change the situation rather than expecting the child to change.
If things help your child such as technology/ fidget toys never take them away in punishment. It's reasonable to set boundaries ie no iPad after 8pm (with plenty of warning:planning) but don't take something that stabilises child away as a consequence
Don't set child up to fail if they can't cope with something don't do it or if you have to appreciate how difficult it is for child and ensure they have things to help through it ie toys, technology, books.
Don't expect child to be 'normal'
Make sure school/child care support child. If diagnosed make sure there's a Sen plan or ehcp in place and ensure school follow it.
Understand if child has sensory issues - fabrics, foods etc don't force child to wear clothes that are uncomfortable or eat foods that they find repulsive.
Try an have a good routine with consistency and opportunity for plenty of sleep. Make sure your child can take sensory breaks if struggling.
Lots of opportunity for physical activity such as running, bouncing, climbing to burn energy.
A good theory to explain neuro diversity is spoon theory. The spoons represent ability to manage tasks/daily life. a person has 10 spoons - having all 10 means happy/settled, having 0 spoons is total meltdown, So if child struggles socially but has to go to an event this might use 7 spoons so they would then need a lot of support for rest of day as only have a few spoons left. Wearing an itchy jumper might take 2 spoons or a change of plan might take 8 spoons. Get to know your child's triggers and help them hold on to as many of their spoons as possible.
I hope some of this helps obviously it may not all be relevant just tried to cover a range of scenarios. Agree Nhs diagnosis leaves you stranded. We found lots of reading, speaking to other families/adults . Getting support from professionals, my son has been under speech therapist, occupational therapist and ASCETS support school. Plus has one to one in school.