I arrive from Amsterdam at Gare du Nord at 9:27 am on Friday, September 7, 2018. I booked a day trip to Vaux-le-Visconte. When can I catch the next RER train from Gare de lest to Verneuil L'Etang train station?
Transilien P trains travel between Gare de l'Est and Verneuil L'Etang once per hour at 46 minutes past the hour. So the next Transilien P train from Gare de l'Est to Vaux le Vicomte area would be 09:46 for you.