Yes, and no.
The earlier interventions are put in place, the better her chances at independence at a later stage.
My son was diagnosed aged 3, non verbal, in nappies, hyperactive, didn't seem to need routine, in fact routines set a precendence for anticipation which caused more anxiety.
We've had 3 rounds of speech and language therapy on the NHS, and the first 2 rounds we took at face value, and it didn't help much, but it was things like intensive interaction, attention autism etc. Between the second and third round, I did my own research on gestalt language processing, and we got our own tablet with AAC. The SALT team were against AAC at the time because they thought it would create a dependence on using technology, and he'd never learn to speak.
I had a few issues with this because a. so what? If he never learns to speak verbally, why should he have other communication channels inhibited, and b. that's not how gestalt language processing works, but they did admit that they'd had no training on gestalt language processing.
I basically had to become a SALT in gestalt language processing myself, doing hours of research and courses and finding people in similar situations to me. A fantastic account on Tiktok if you're on there is Mama and Tommy. She also had to get her own accreditations to get people to take her seriously, but now she posts so many videos advocating for the use of AAC and it's benefits and her account has been running for years and you can really see the difference it has made for her child.
My son is 6 now, almost 7, and can speak, but he's not conversational. He has what is called idiosyncratic speech. He absolutely fully understands what's being said to him, he can follow instructions, he can even tell you what it is he wants or needs, but he won't always respond to questions, and he can't follow the curriculum at school, and unless you know what his echolalia sentences mean, then it can be hard to understand sometimes what is being asked of him, but every month he is progressing and sometimes he'll come out with sentences that he's not seen on TV. An example would be that his dad had surgery on his knee, and he spontaneously asked "Daddy, did that hurt?" and my brother also got a tattoo of Squirtle, the pokemon, and my son said "Wow, I love your squirtle tattoo, do you like pokemon too?" and these are all spontaneous sentences that he's formed without this specific language being modelled to him.
At 3, I never would have imagined this possible. When your kid gets a diagnosis as young as 3, you think wow this is my life.
The thing is, even if he appears to catch up in 5, even 10 years time with his speech, speech isn't just talking, it's understanding and processing, and a speech delayed child will always have difficulties in these areas, they just become less apparent, and that's when it starts to affect relationships and friendships because there will always be misunderstandings and miscommunications. This is what happened with my brother who didn't get any gestalt language processing support, but just had to acquire this language later on in life and didn't get a diagnosis because of the lack of understanding of the different ways autism presents, and he was sort of this SEN-betweener where he was delayed enough for it to affect his development and progress, but not delayed enough for medical professionals to offer any interventions.
My son is 6, and is still in nappies. We've tried everything. I've been on more parenting courses and seminars and webinars and I'm sure the people at ERIC know me on a first name basis now. We've spent a small fortune on tools, and pottys. I have over the past 3 years been involved in lots of communities of SEN parents and children, and even autistic children with significantly higher needs than my son have been able to potty train, so sometimes it does feel like a kick in the teeth, but I have also been privileged enough to live next to somebody with a child who is older than my child with high needs autism, who has had significant developmental challenges, and has overcome them in his own time. He is about 10 now, and it's only in the past 2 years that he's learned to talk, and stopped using nappies, but those changes happened when they'd finally won their battle and gotten him into the right school.
He's a right little chatterbox now, in fact I'd say the trouble he has now is knowing when to stop talking which is no bother to me, I feel he's earned the right to chew an ear or two off if he wants to, but obviously it will go on to affect his friendships and relationships too.
The hyperactivity for my son has just gotten worse, but now we're seeking an ADHD diagnosis too, which we've not been able to until now due to the age constraints on diagnosing ADHD in children.
The best piece of advice I could give you is start the EHCP process yourself now through your councils website, even if she's not in school, because my son has had to resit reception 3 times, and although he's had an EHCP since the first year in reception, we're only just now at the point where the LA have acknowledged that he does need a full time specialist provision, whereas if I'd have known at 3 that I could start this process myself, I think we genuinely could just have gotten straight into a specialist school when the mandatory applications for school came about as many SpEd schools requirements was simply that an EHCP was in place.
The right school that caters to the right need, which in my sons case is social communication and interaction, will have far more training, understanding and access to community and educational resources to not just support your child academically in a way that meets their learning and play style, but will have faster access to support like speech and language support, and usually have smaller class sizes, or a smaller staff to pupil ratio as standard. The one we are looking at still has class sizes of 30, but has 3 pupils to 1 adult, with 1:1 or 2:1 if stated in the EHCP, and many focus heavily on life skills, helping the children to learn how to be independent rather than focus solely on academic skills which can be picked up later in life if needed anyway.
Your daughter will always have this disability. It is a lifelong disability, and her inability to speak now doesn't mean she'll never speak. And even if she never verbally speaks words, it doesn't mean she'll never be able to communicate through AAC, it doesn't mean she'll not understand what's being said to her, it's just right now the language centre of her brain isn't matching up with the muscle movements part of her brain so the way the mouth moves to make speech doesn't come naturally to her like it would for a child who is neurotypical but with the right support it doesn't mean that all her words need to stay stuck in her head and she will be able to find a way to communicate with you.