If that's your biggest concern and you aren't bothered by having to pass people I would suggest seeding to the outside of the pack at the start and don't start swimming until the people around have already started. Just make sure you sight frequently so you don't end up way off to the side. The pack should thin within the first few 100 m. So you're job is to swim the most direct line to the bouy regardless of where you start out. If you start out at the side, by the time you come back into the main line of the swimmers, they should be all thinned out. Just watch that you stay within the boundries of the start area. If you go outside of the boundries, someone will say something over the PA and you just correct your position.