OK, every 5 days it is. All the rodent sales sites tell how long the mice are, and how much they weigh. The care info talks about how big around the mice should be.
Hence my confusion about the size. I'm new to this, and asked the salesman I bought Fang from what food to use, so I bought pinkies, and they are most definitely NOT as big around as the snake. I'll order some weanling mice today.