Advance train tickets from Paris to Beaune?

check with the Man in Seat 61 about whether it's worth buying in advance, and also the need for seat reservations

If the schedule that works best for you is for a TER train, then it makes no difference when you buy because the price does not change. If the schedule that works best for you is TGV, then buying now may mean lower prices but less flexibility for changing your plans without having a change fee. I have never seen cheaper tickets closer to the date of travel. How advantageous it is to purchase the tickets now depends on the price difference. You can find the price of a ticket for the train that leaves tomorrow at the same time that the one you want to take on September 22nd leaves and see if the fare difference makes a difference to you. And yes TGV trains can sometimes sell out. I don't know if that happens often enough to be a real risk. It's happened to me twice in the past 14 years.

Paris to Dijon is a TGV and you switch to a TER local train to Beaune. Don't buy an itinerary that takes you to Lyon on your way to Beaune although it's offered on SNCFConnect. It's too long and out of the way.

From Beaune to Geneva, you take a TER local train from Beaune to Lyon where you change to another TER local to Geneva.

I buy my TER train tickets online before a trip because it's more convenient for me than rushing into a station and using a machine, but seating is open and they rarely stop selling these local tickets. The price is the same no matter when you buy a TER ticket.

Your only TGV is the Paris Dijon train, so yes, go to SCNF Connect and buy a Paris-Beaune ticket for your date via Dijon. This will give you both your TGV and TER ticket for that day. TGV tickets increase in price over time.

I'd purchase now. The best deals are available early. There are discounted fares available early that sell out. Some trains sell out completely, so you lock in the time you want as well. If you wait, you will still figure something out - but it will cost more, sometimes significantly more, and you will haven fewer options.

Baune to Lausanne the best route is actually back to Dijon by TER, and then on the TGV from there. Via Lyon is a detour. I would take the 8:59 departure, and buy tickets now, as they are only going to get more expensive.

The same rule as always applies: Do not make any a priori assumptions about the best route. Let the railways find that for you.

Thank you all for your help! I will purchase the tickets now. Your information and advice is much appreciated.

Yes. There’s one TGV from Dijon to Lausanne a day. This is the best and less expensive.
TER 17754 from Beaune to Dijon, changing to TGV Lyria 9261 Dijon to Laussanne.
Good find. This didn’t pop up on my search.

Bets and WengenK,
I found the 8:59 one from Beaune to Dijon, then TGV to Lausanne! Already booked it! Thanks again!