The most important aspect of sitting at the drums is to keep your back straight. This gives you maximum reach and avoids the possibility of muscle strains. Start by sitting with the snare drum directly in front of you. The exact distance is a personal choice, experiment until you feel comfortable with the position of both the drum stool and the snare drum.
When setting up the position of the drum stool and the kit, make sure you can reach all the drums and cymbals easily without having to lean or stretch. Also make sure that everything is far apart enough that your arm movement is not restricted. The most important thing is to be in a relaxed and comfortable position when you are playing.