I have only been to one TBF before so others will probably be able to chime in here, but in my experience it just depends on how close you want to set up shop/homebase. We ended up pretty far back in the line each day knowing that we'd be back and forth from the front but that we didn't care where we set up our tarp -- in other words, we didn't do the tarp run; we just got in the line to get in and were in by the time the first act started every day if we got in line around 9 or 9:30 with a spot where we could see but it was relatively comparable to what you'd see from the back of the pavilion in a standard amphitheater show, maybe even a bit closer (we needed space for about 8 and just decided to take it easy in the mornings instead of waiting out in the line!)
In other words, in my experience you'd be fine waiting depending on your needs, but (obviously, I hope) the later you get in the fewer spots you'll have to choose from. And obviously as a group of two, you'd take up less space and would have more of a chance of finding a closer spot to squeeze into.
Maybe that helps? Who knows.
Listening to:
that excited sound that exists in the quiet house when you're going to start your journey toward TBF in the morning