Reading this, I have two concerns.
First, owning a dog when you have little money is hard. I've been there. When I bought my dog, I was on minimum benefits while working two part time jobs. I would not have bought Brodie when I did had I not had the approval of my parents. (Sorry, Roxie. I know you'll hate me for that

). Thankfully, I never needed to ask them for a loan, but it's not a situation I'd be willing to experience again. The financial strain was eventually one of the many triggers that got me my first hospital admission.
Secondly, and this is just my own experience, the use of a dog, be it a SD or just an in-home ESD is most effective when partnered with coping skills that are already effective. I used to suffer from debilitating panic attacks. By the time I'd got Brodie (after two years of weekly CBT sessions), I'd got to the point where they only appeared during episodes of acute mental illness. With Brodie's help, I got better at managing them to a point where I usually recover in minutes. But, had I got Brodie before the CBT, I'd be unable to leave the house without him. I'm maybe describing it as clearly as I'd like, but in my opinion, a SD is not an alternative to medical treatment and therapy to learn coping skills. However, once you acquire these skills unaided, your dog can turn them into something truly wonderful.
Finally, by getting a dog before you learn to manage on your own, you would miss out on the huge sense of achievement from managing yourself. After all, who wants to have to give half credit for their own work to someone else, even if the someone else is four-legged?
But keep in mind, my opinion on this may be unusual: I HAVE to be able to manage alone. I live in a country where legally recognised owner trained service dogs do not exist in any form whatsoever. My own dog may be task trained with as much socialization as a PSD would normally have had, but I will never have public access rights for him.