I extend the factory-cut tab to about 2x its original legnth (index finger to pinky where they meet the palm).
I bought a good pair of curved cuticle scissors at the drugstore expressly for trimming leader for the LTM. Works well.
I buy my film in four-packs, so I do four rolls at one sitting.
I have also tried loading with the film just as it comes from the mfr ("short leader") , but I have to remove the lens, set the shutter open on "Z", and ease the film up past the top edge of the gate from the lens side...
In any case, after winding about 1/2 wrap onto the take-up spool, I tighten the re-wind knob, and make sure the film has engaged the sprocket teeth.
I had a similar "film-split" disaster with a "new" black III... 1/2 of the split wound-up getting rolled into the shutter-blind on the advance-knob side, with film chips jamming the gears in the bottom of the shutter crate. 😕 😱 😡
This required my first (and so far, only ) adventure into taking-apart a Barnack camera... patient and doctor both survived the proceedure ! 😎
Have had dozens of trouble-free bottom loads since then.
Good luck !