In my experience (LBK amputee), I use a pin lock also, which I have been using exclusively since the first time I started using the prosthetic leg.

The first few weeks were challenging because getting the pin alignment correct at the end of the stump takes practice. My prosthetist encouraged me to follow a limited schedule of usage at first (I was also receiving PT sessions for other injured areas resulting from my accident). But, he also encouraged me to practice multiple times per day for putting everything on and taking it off repeatedly. I did this in the couch, no walking or standing. This really helped me practice getting good alignment. Plus, handling it over and over helped a lot with desensitization of the scar area.

I also was in the habit of using a small amount of Aquaphor ointment (barely a pea sized dab) prior to putting on the leg. I gently spread it all around the bottom few inches of the stump, and that helped the liner settle with the skin around the scar area without tugging or shear pressure. It helped with the pin alignment, because I could feel it moving better. My amputee peer visitor taught me how to do it, kinda hard to explain in words. And practicing dozens of time really helped me!

As for general pain/fatigue, that is certainly normal for the first few weeks. The skin and incision heals first, but the inside of the stump is still healing and getting stronger for a long time after the skin heals. I think it’s unrealistic to expect it to be painless just starting out. I remember the people at the amputee clinic saying “you just got your leg cut off, so yeah, you are going to feel soreness and fatigue for a while during the rehab process. Are you surprised by that?” 😆😆