Will agree 100% on what you said about the forum and the members here. I have gotten so much feedback and support in my quest to start this hobby, it has been amazing. I check here daily and will read what I can. I may try the brew in a bag soon, but for now, I am just taking in all I can and learning as I go.
I am really excited for you, it looks like you're going to have a lot of fun with this. (I started reading this forum religiously for almost a year before I finally registered an account, wish I hadn't waited.)
I started out with pre-hopped LME kit (I received a Mr. Beer kit from my daughter as a gift, I had never even thought to do homebrewing before her nudge); and then I bought another pre-hopped LME kit from Brewferm and some specialty grains for steeping, to experiment with modifying the LME kit. I think it was my 4th brew wherein I did an actual mash & BIAB on the stovetop. I've been making incremental tweaks and changes with pretty much every brew, still fine-tuning my process (including sometimes taking a step back from . I made quite a few 'mistakes' (or rather, less-than-optimal methods) and along the way I learned that not every 'right' way was best for me.
I don't think there is a "best time" to go all-grain; it depends on your own comfort level, confidence, willingness to make 'learning mistakes' and not get disillusioned by it, and depth of research. I really like Denny's threefold mantra, and finding that balance point between ease, quality, and enjoyment is going to be different for everyone. There have been batches where I've put a lot more effort into making a better beer, and I didn't enjoy it as much. I take shortcuts that I deem justifiable for me.
For many decades, I would dream about getting back in a band again, and in my spare time I was composing music that I never recorded and never performed, but I still enjoyed playing it for myself. With a lot more effort and a lot more money, maybe some of those songs could've been big hits, or at least enjoyed by crowds... and those songs never got the chance. I'm the only one who ever heard them (well, my wife and kids did too). But that's ok, they were my songs, and I enjoyed playing them for myself, and that was good enough.
That's how homebrewing is for me. You're ready to switch over to all-grain or BIAB or whatever other process-modification, when you want to try it.