My girlfriend and I are due to catch a train from Tours to Paris Austerlitz tomorrow, and we need to switch trains at Orléans, with a 12 minute gap between our scheduled arrival at and departure from there. As my girlfriend is pregnant, I want to minimise the walking distance between the two trains and wish to know the best place to board at Tours to do this. Should we get on the first carriage we come to after walking into the platform at Tours, or should we walk all the way to the end of the train before boarding?
Both Tours and Orléans are terminus stations, so to change platforms you'll need to walk all the way to the front of the train (as far as I can tell there is no underpass in Orléans, and anyway your girlfriend probably prefers a level walk).
It's possible that the trains will be on opposite tracks of the same platform, I don't know what the track configuration is in Orléans. Note that in France, trains don't always stop at the same tracks from one day to the next (of course sometimes the track configuration doesn't leave a choice).
If you have Internet access, you can look up schedules and platforms for upcoming departures and arrivals, but the track will not be announced until a few minutes before the due time.
I've never been in Orléans, so if a local gives you contradicting information, trust them, not me. Not everyone in France speaks English, but if you ask around you'll probably find someone who can help you.
Anyway, given the lengths of the trains, 12 minutes should be plenty. Even if your train is delayed, the train to Paris should wait until the platform has cleared up.