Odeon to Gare de Lyon for early Saturday morning train.

The easiest and quickest seems to be the No 4 Metro to Chatelet, then the No 14 Metro to Gare de Lyon. At least all of the No 14 line has elevators and/or escalators at all stations. For wheel chair accessible stations (thus elevators) suggests walk to to St Michel and use the RER B to get to Les Halles and change to the No 14.

The app does show the first 87 bus at 6:26 getting to GDL at 6:37, although the printed schedule shows first bus leaving Champs de Mars at 7:00 on Saturdays, so a bit later before it would reach Odeon/St Germain.

Seat61 guide to Gare de Lyon: http://www.seat61.com/stations/paris-gare-de-lyon.htm#.V9Kx1SgrLIU

Sam had the info. Here's a RATP Link that shows the same info. Why do you want to be at the station so early? If you're there 20 minutes prior to departure, it should be plenty of time. Technically, you can board till they might close the gates 5 minutes prior to scheduled departure.

Neurotically early, always expecting to get lost en route. It's just how I roll.

If you are really that neurotic, you might think about taking a taxi, which would cost you less than 20 EU and would take you about 17 minutes.
There is absolutely no point in leaving 2 hours before your train leaves, because nothing much will be open.
Gare de Lyon is not difficult at all - here's a helpful link that will walk you through finding your connection:
http://www.garedelyon.fr/tourists/

The 63 bus goes directly from Odéon to the Gare de Lyon. Go to catch it at 7:00, and you'll be fine (6:45 if you want to be neurotically early - the bus will sail through the non-existent Saturday morning traffic). Two euros if you buy the ticket from the bus driver (have exact change); of course less if you've bought a carnet or tickets ahead of time.

Bus 63, or bus 87 will be the quickest and easiest. I would plan to leave no later than 7:00.

I usually check my RATP app to see when the next bus is coming in hopes of minimizing my wait time.

Thanks everyone for their input. I will probably take the Metro, arrive early, have a coffee and wait for the train.
A little backstory: After my husband died, everyone expected that at 62 I would stop traveling. That was 6 years ago, and I'm still going strong, on my own. I need a bit more time than most travelers, and I certainly have to plan everything out in advance. That's where the Traveler's Forum has been so helpful. So again, thank you all.

PS I think travel wards off Alzheimer's. Sure beats computer games.

Obviously, it's your choice. But the bus will be 10 times easier than the metro. There are no stairs to deal with and on either line it's a straight shot, and less than 20 minutes to Gare de Lyon. Both busses stop at the same spot - right next to the metro at Odeon.

I prefer taking the bus whenever possible as do most of my friends who live in Paris.

Fist of all, three cheers for you and your continuing travels! As a fellow neurotic, and somewhat obsessive, travel planner, I might consider taking a trial run on the bus. Maybe there is something in the area or along the way that might be interesting to see to help justify the trip.

I second Parisonadime's emphasis that the bus is SO much easier for this route than the metro. Save yourself the up and down stairs, you couldn't be better placed (with your hotel being at Odéon) to be able to jump on and off the bus to get to that particular rail station!! And at that time of day, again, no worry about getting stuck in traffic. Please do take the bus!! The 63's end point is the Gare de Lyon, so that's what's written on the front and sides of the bus! You can't miss it (either the correct bus or the correct stop).

Good luck and good for you for keeping on with your traveling explorations.

The first 63 bus is at 6:50 on a Saturday and shows it taking 6 minutes to get to GdL. So not much need to walk out of the hotel at 6:00.

OK..the no. 63 at 0650 it is! Thanks