Excited for you on the beginning of your modular journey!
I will +1 the opinion that creating a small setup is a reasonable approach, even for someone new to modular. I've gotten much enjoyment from my first (and still unfilled) 84HP rack and am glad I didn't start big. By having just a few modules, I push each one's capabilities, and push myself to learn things really well, without breaking the bank. And if I'm not really vibing with a module 100%, I trade it and send it on its way to a new home.
In addition to reading reviews/watching videos, the most helpful approaches and resources to me when I was planning my first small setup were:
Reading the manuals of modules I was interested in before making a purchase. Often a feature I assumed was there was not, the voltage range was too small for my purposes, etc.
Building a "dream setup" like you've done and then sketching out patches in ModularGrid or VCV rack beginning to end. I would think, "OK, I want a bass lead... that's a square wave... with pitch I can control... from a sequencer... but I need less attack, so..." I did this exercise for entire imagined songs. This helped me see which features were either maxed out or unused. I actually created a ModularGrid rack that was three times larger than my actual target case size. It was a great way to keep two rows of "maybes" while I planned.
Trying it out for real, one or two pieces at a time. If you can't try before you buy in a shop or with a friend, purchase online. Worst case, many retailers offer 30-day return policies with a modest restocking fee, or modules can be resold independently for near-MSRP, as they hold value well when in good condition. There are affordable multipurpose modules, like the much-maligned Cre8Audio Mr. Phil Ter (Filter + VCA + EG for $100), that can let you get hands-on with multiple features to learn what you need more or less of without incurring a huge financial risk. You may not keep it forever, but something like that is a good learning tool that will also give insight on other things you may not have considered, like "Can I turn these tiny dials?" or "Do I really need voltage control of [parameter XYZ]?" or "Can I cope if this feature doesn't have an LED indicator?" (For me, the prospect of spending $400+ for a suite of "proper" filters, VCAs, and EGs was pretty daunting when I didn't know what would prove useful for me personally. And I feel guilty when I spend a lot of money on something only to not get much use out of it.)
Researching brands. There are some brands I won't buy out of ethical concerns. Not everyone feels that way, but I recommend doing the research before you rack something if that kind of thing matters to you.
Just my $0.02. Good luck; have fun!
Every ModularGrid forum post is just the same three guys telling beginners "No offense, but you don't understand Eurorack well enough to start Eurorack" over and over until the sun explodes.