Chamonix in January

Hi we are taking a ski holiday to Chamonix in January. Our flights are into Paris and out of Geneva, so after a few nights in Paris we plan to take the train to Chamonix. I understand that we can take a high speed TGV train from Paris but will have to transfer to a narrow gauge rail line to get to Chamonix. Unfortunately there is some issue with the route from Paris to Saint Gervais Les Bains Le Fayet and it is still listed as "not bookable yet" for Sat Jan 17. The surrounding dates are bookable to Chamonix on "alternative route" through Albertville, but there is nothing on our date. I can 1. be patient and hope this sorts itself out. Or 2. Book a direct train to Geneva then catch a local train from there on to Chamonix. Both trips are just under 7 hours in total travel time including about a 1 hour transfer. But the Paris-Saint Gervais route is 5.25 hours on the TGV train and 45 minutes on the local train and the Paris-Geneva route is 3.25 on the TGV and 2.75 on a local train. The local segments aren't available to book yet, which is no worry, we are happy to sort that out on the day of travel, but I am just looking for someone who knows this route and can tell us which is likely a better journey for 4 adults who are looking to enjoy the trip in a club quatre. Also any intel you have on the 'not bookable yet' which apparently can mean anything from sold out to engineering works on the line. I realize that I am being a bit impatient, but how long is too long to wait for this route to open? I would just rather not wait until the last minute because we have very specific travel dates/times. Last time I did this trip we flew into Geneva and hired a private transfer, but one of our travel party gets very motion sick in cars and prefers the train. Thanks so much for your feedback and thoughts or alternatives!