when you feed your snake, look for a lump in the stomach. if you don't see one, go a little larger the next feeding. the lump shouldn't be huge but you should be able to tell that the snake just ate. as long as you can see this, you don't have to worry about 2 mice until it get big enough and a large mouse can't be seen. and don't worry about feeding mice. I have a few females that are mice feeders and they are over 4000 grams. they eat somewhere around 2 to 3 mice and I offer every 3 days. you will get to know what and how much to feed your snake by feeding and seeing the results.