+1 to what PeWe says above. I use a couple of the plywood scrap bits in my first post photo, to hold the bead down in the “valley” opposite where I am pulling the bead over the rim.
If you look closely in PeWe’s last photo, you will see a raised line on the tire sidewall, just above the edge of the rim. When you are finished and inflated, make sure that line appears consistently around the rim. If it disappears below the rim at any point, deflate, break the bead in that area, lubricate and try again. Get it perfectly even, all around.