I "box it in" with lightly sketched lines that show certain main edges of the house like the top ridge of the roof, the bottom foundation edge, and maybe the roof edge over the porch. Same with side. Sketch details in slowly, but modify or adjust as needed. I don't actually use a vanishing point, just eyeball it. It takes practice.
I had that weird uncanny ability even as a kid. I think many people can't get it somehow, only a few. Maybe it's a curse! But yes, I practiced hundreds or thousands of hours doing perspective sketches. Also, I tried the mechanical way with two vanishing points and a floorplan laid out on your table (old-fashioned and complicated, how "they" used to do it, and you need a huge desk!) but it didn't result in anything any better, maybe even inferior.