I've been rock climbing and mountaineering for the past decade and a half. I've done a little bit in the Cascades and British Columbia, and a ton out in Yosemite, the High Sierra, and all throughout the desert southwest. I actually got my start by taking advice on an old Air Force forum (AFEF) from a SOF support guy back in the day which led to quite a few years living out of my truck chasing sunny, dry rock to climb after I got off of active duty.
There are plenty of good options stateside to get you prepped for Mont Blanc. I would recommend trying to get in a trip next summer out west somewhere to get some climbing and crampon/ice-axe practice. Somewhere in the Cascades or British Columbia would be best. If you still have some GI Bill left, the
American Alpine Institute is an outstanding guide/instruction service based out of Bellingham, WA that
takes the GI Bill for its "Alpine Mountaineering and Technical Leadership"
courses. The first course is a 12-day course taught up in the North Cascades. The instructors are guides, but it is heavy on instruction and teaching you the skills you need to be successful--not just dragging you up the mountain to tag the summit. You can always just hire guides to drag your ass up, but I think it is more safe, more fun, and way more rewarding in the long run to really learn the shit yourself and learn how to keep yourself safe and make good risk decisions in the mountains. Even if you can't do it for free through the GI Bill, it is well worth the money you'll spend out of pocket.
Even if you don't do AAI, I'd still look for a way to get some instruction and mileage on rock/ice/snow this summer if you can. It will help force you to focus on getting in shape for the summer, it will give you a good gut check at where your body and head is, and it will also reveal issues with gear/clothing that you will want to resolve before you head for a bigger objective. Flying all the way over to Europe to do Mont Blanc only to get shut down by preventable issues would suck.
Also, I've tried a bunch of different mountain training plans over the years, and I've come to really rely on and trust Rob Schaul's plans over at
Mountain Tactical Institute. Rob is based out of Jackson, WY and he basically writes the curriculum for Exum's guide training (the premier guide service in the Grand Tetons outside of Jackson). He's got a ton of plans focused on either SOF prep or mountain athlete training (climbing, mountaineering, backcountry skiing, guiding... etc). His programs are practical, well-rounded, and directly applicable to the fitness you need in the mountains. The ones that I'd take a look at if I were in your shoes are:
Feel free to shoot me a message with any specific questions you have. Climbing led to me living/working in Yosemite for a quite a few years and I've seen lots of good ways to get into it as well as lots of shitty and dangerous ways to do it. I've also got a really good friend who is a senior mountain guide out with
Alpenglow Expeditions in California if you were looking for some one-on-one instruction or guiding. Let me know. Good luck!