USAT Timing on wave starts

When your wave starts. No matter what time you cross the start line. The computers look at your chip times and your listed wave start time to figure elapsed time.

I missed my wave start once, struggling into my wetsuit, and just knew my time showed me about 2 minutes slower than I was.

From my experiences, they adjust your time to "chip" time instead of 'clock" time.  Example, one tri last year, I was in the last wave to start, 55 minutes after the first group started.  At the finish line the clock read 2:10:00, however the results listed my finish at 1:15:00.  Hope that helps. 

You are assumed to have started with your wave in most of the ones I've done. Others have a timing mat and only those who are going into the water for the next wave are allowed in the start area so they know you were in with your wave.