I tell you... start from Genesis 9. I said that by experience. Having too many options when you start learning a new tool always ends up working against your progress. it takes you over, increasing your urge to collect and do more than you can handle. And that's the main reason. The other reason, and not a less important one, starting with the latest newest resource or in case of my work with Unreal Engine 5 to which I switched immediately allow to not loose you in the gap. First you can stay ahead of others who, procrastinating the deal with the new wild beast to tame, have to reduce the gap with whoever didn't the same and decided to tame the wild beast instead.
Second, you're "learning by doing", which means your skills evolve with the evolution of the new tool and of the latest newest features or range of items that new tool provides you. What also happens is that problem solving will become part of your skillset which is, in my opinion, the most important aspect of such an approach.
This is my very personal opinion, of course, but in 35+ years of professional life I think I've learnt a thing or two, including which mistakes I'd have better avoided when I had the chance to do things right and those I managed to evade. In any case... do as you feel better for yourself. The approach I suggested is a bold, sometime aggressive, but in the long run always pays off. if you wanna be more cautious because that's how you are then go for that approach instead.
Ultimately by the way... the solution is quite often in choosing the hybrid position and work on both. Just don't be afraid of being bold when is needed or when the proper opportunity comes.
Enjoy your new creative journey and b cool!
PS: a lot does also the rig you're using. That's an element that helps a lot in taking a decision. if your computer can't handle some of the crazy stuff we might encounter with some items, the choice of avoiding them is inevitable.
