I don’t know where to start

Hi I’d like to start a veggie and fruit garden but I have no idea where to start. I’ve decided to design my garden in my artbook. I know what I want it to look like and i have a rough idea of what I want to grow ie herbs, veggies like sugar/golden nugget pumpkins, snap peas, zucchini, garlic, shallots, carrots and root veggies. I’d also like to grow some patio ttrees (cherry and pears) and strawberries and some flowers. My garden isn’t very big but I’ve designed it around my garden so I can do it. The issue is I don’t know when to start. I understand the basics of compost put in any organic scaps with worms and it magically turns into dirt over time but I’d looked at pictures and is it really worthwhile for such little dirt ? Can I just use store brought? Is it as good as homegrown compost? I can show you my garden and my design if your interested too _^