The position depends on a lot of things. Chief starter for 76 Olympics always was on the infield about 26m in from lane 4 to make the distance about that same to all lanes. Still needed extra recallers that were about 5 m in front of the main starter. one would look at the first 4 lanes,the second would look at the last 4. all people with a gun would stand to see each other and have hand signals arranged for readiness of "on your marks" and set positions. If you have multiple Speakers/ PA's starting from rear or anywhere that gives a good view will work but be careful that if using only 2 speakers that they are not two far apart. At one meet I saw people think that there were recall guns going off because the speakers were causing an echo effect.