Rendez-vous at Vaucresson station at 9:40, arrival of a train leaving St Lazare at 9:09. This train passes through La Defense at 9:20.
Ile de France Walks does Wednesday hikes in the Paris region. About half of us are English-speaking French. The rest are other English-speaking people from a wide variety of nationalities. Walks are free, and there's no need to sign up in advance. Just show up in good time, tickets in hand, at the meeting place indicated below.