Well, that shouldn't stop you from at least getting Daz Studio, and just mess around with it for now. I still have to actually start on some small VN I want to make, and didn't look into Ren'py at all yet. But, I have a blast rendering my own backgrounds for my mobile phone, and it's definitely educational to just figure out now what all those sliders and stuff do. I started doing that on my previous computer already, on which I could only do slow CPU renders. I'd just spend an evening once in a while to set up a nice scene, let it render over night, and hope something decent came out by the time I woke up in the morning. Just, don't go crazy buying models and stuff, it can turn into an expensive hobby very quickly.
And, there's a downside to having a ton of models, that very few people mention: it actually slows down Daz Studio, even if you don't have a model loaded. Just having it installed will add to the time it takes to load another model. At first it's barely noticable, but even a new computer can get pretty slow from having some fifty+ models installed..