First, I'm really happy you're trying to transition to veganism! There are plenty of dark chocolate, chocolate with oat milk, crackers, cookies, snacks, etc that are vegan Also, if you make a mistake when you're starting out, give yourself some grace and just remember that for next time.
I was vegetarian for 6 years before I had some realizations and became vegan. I went quasi-all in overnight in that I didn't intentionally buy myself anything with animal products in it from that day on. However, I detest waste, so I did not throw out any food, clothes, etc that I already had that contained animal products. I gave away some of the food I had that was unopened, but I had a half full shaker of parmesan cheese that I was using for the next few months.
I think that mental cutoff while still being able to eat some things if I was really missing them helped, especially since you're more likely to already have foods you enjoy. I knew I wasn't contributing to additional animal cruelty, environmental destruction, exploitation of workers, etc, but I got a final goodbye to a lot of things.
Honestly, the less you eat things, the less you want them. I grew up eating literal bricks of cheese: I'd just eat half a block of smoked gouda or sharp cheddar for lunch (maybe with crackers). Now I don't even want cheese; I can't think of the last time I specifically thought, "oh dang I should put cheese on this". I've only bought alternative cheese when it was on clearance sale so I could try it out to advise others. My big thing was not buying any more Greek yogurt, but there's a ton of almond, coconut, oat, and soy alternatives. They're more expensive, but I'd just wait for sales and then stock up. Now I don't really look for them, if they're less than what I used to buy Greek yogurt for, I'll get them, but otherwise I'd rather just buy vegetables and vegan ice cream instead lol.