I had to migrate from a 5/8" sewing seam to a 1/4" quilting seam. As long as you stay with simple patterns and you can sew a consistent seam allowance, you will have no problems. But if you get into wanting to advance into piecing with triangles and other shapes, maybe it is best to learn to adjust now. It might be harder in the future. But just be consistent.
With dogs, I would make them out of sturdy fabric like denim that will take the wear and tear from their nails. Cotton won't hold up long.