I take it you are feeding dead mice? If so it doesn't matter. Feed as many as you like, as many as it will eat. Snakes basically sleep and hunt so let it sleep off its meal.
You'll know when its ready for its next meal (a week to a month depending on its growth rate and whether its shedding) when it starts exploring its cage.
If you're feeding live mice, that's a whole different question with very different answers!