It depends so much on what kinds of quilts you're going to make (size of the quilt, how big the pieces are, how many different fabrics), and since you're new, you probably don't know yet what you'll end up doing most, and it will probably change over time.
If you weren't so far from the fabric store, I'd suggest starting by planning the quilt and buying what you need for it (plus extra in case you change your mind or make a mistake). But since it's a drive, I can see wanting to get some on hand. If it's not a strain on your budget, 3-4 yards would not be unreasonable.
I like to buy 2-3 yards, but sometimes when I'm trying to plan a quilt it ends up not being enough, yet it's way more I'd need for a scrappy quilt. That's why these days I'm going back to (TRYING TO) plan my quilts and buying what I need for them.
I've also learned to only buy fabrics that I love and not buy something just because it's inexpensive. Even if it's just some tonal fabic, I like some a lot more than others. I'll use anything in a scrappy quilt, because it doesn't matter as much and I don't have a big enough stash to be choosy, but when the quilt has only a few fabrics in it, I'm reaching for the fabrics I love.