You can go to BART.gov the site has a trip planner you can enter what time you need to be at your destination, and it will advise you what train take. I would also plan on time to park, parking is limited at Antioch BART
IT TAKES ABOUT 10 TO 15 MINS TO GET TO THE WALNUT CREEK STATION, HOWEVER, YOU WILL NEED TO FIND OUT WHAT TIME THE TRAIN LEAVES.
Thanks! Your answer is awaiting moderation.