Sit them down... then LISTEN
Question: How do you form this trusting relationship in a short period of time?
Answer: Find a way to show that your objectives are aligned, you are willing to listen, and you are on THEIR team.
Hint: Don't make the assumption that it's only about winning games and winning a championship at the end of the season. Remember WIIFM (What's in it for me? And me is them!)
Keep that list with you throughout the season. Soon every note will be in your head as you watch and coach each athlete because you will be using it. Take some time to plan specifically how to help them with their goal. When you get those one-on-one opportunities, coach them up on their goal. Commend their progress or make a suggestion how to adjust their technique to help them progress. Now you are showing them that YOU are working for them. You are listening to them. It's a natural human quality that we listen to those who understand us and whose objectives we understand are aligned with ours. Now you are working together and you are a part of THEIR team.