With the number of chapters, yeah, 300 is quite early. But it's a slow burn because it takes like...I think 3 arcs? for them to get together, and there's a bunch of stuff going on at the same time.
There's also layers to their relationship because of both Yuder and Kishiar, so getting together is like the...maybe 3rd layer lol we still have a bit more to go. In fact, there's another layer that got peeled (that sounds weird but oh well) in the high 500s. There's probably more that I don't know because I don't read raws. So yes, they get together fairly early on, but not quite all the way if that makes sense.
IS THE ABO LIKE THE USUAL ONE? CAN YUDER GET PREGNANT? JUST. TELL ME.