Sorry, I am not Steve, Mark, or anyone at UA, but I did just hike Kili in January of 2022 via Lemosho (think I started on the 6th funnily enough). If you are following the routine and feel fit and strong that will go a long way, I personally followed the 16-week big mountain plan but was not as disciplined as I would have liked.
To your question about walking with a daypack, I would certainly say the best way to get ready for walking uphill with a daypack is to walk uphill with a daypack. I would usually do two-three times a week with my pack on loaded up on my treadmill at a max incline for an hour or so and then just get out for longer hikes on the weekend, Kili is a great challenge but certainly an accessible one. If you focus on being fit and doing regular hiking in the lead-up, you’ll be ready! Then the fitter you are the more it will feel like a walk and the more you can enjoy it. I doubt the extra hikes will cause overtraining if they are casual enough but as always listen to your body.
Some things from my personal experience that might be helpful (take them for whatever they are worth)…
– If it’s not too late and you have the chance to get in a day or two early, check out Materuni Falls. Materuni is a village about 30 minutes from Moshi and wherever you’re staying can likely arrange a private tour pretty cheaply. It was not only a nice way to experience some culture but you also get a chance to hike to the falls which are in the foothills of Kili with a little bit of altitude (I want to say 5-6k’) and shake off some jet lag. Really easy hike to get moving and worth the views.
– I found the first two days to be more challenging than I expected. I had been at higher altitudes so was a bit surprised at how worked I felt on days one and two, I think a combination of jet lag, anticipation, and the heat (mostly in the jungle those days) got to me a bit. I was a bit discouraged but it seemed everyone in our group had their days to feel crappy, that was mine and it got way better from there.
– Lava Tower is a great confidence booster day because you are finally getting some serious altitude and feel like you’re doing the thing!
– The guides will be all over it about pack weight, eating enough, water intake, Pole Pole (going slow). They were super helpful and extremely impressive. Enjoy camp and chatting with guides and porters–some great people!
– Summit night is a fantastic experience! Challenging to be sure mainly because of the schedule of getting up to base camp and trying to sleep before the push and then the long trek down can be a slodge, but at that point, you’re basically already there just enjoy getting to the top. The way down can be rough, do not overlook step-downs and exercises to get your knees strong and stable, almost everyone says this is one of the harder parts.
Good luck and enjoy! It’s a stunning mountain!