The reason we teach grip before shins is because we want the hamstrings tight, not slacked, as the chest is set up. I'll leave the mechanics of this for you to explain. And this is just the teaching progression, which means that as you learn to assume the correct position at the start, we don't care how you get there as long as your hips are in the right place and it looks the same every rep. As you begin to do sets of multiple reps without releasing the grip, this will have to happen anyway, i.e. you'll have to learn to find the position without the 5 steps.
I always identify my grip against the bar knurl so I can take the same grip every time. I think your experimentation phase should be severely truncated. Find your grip, take it, and stop fucking around.There are also two problems that can occur with grip width when setting the grip first, either gripping too wide for their stance and increasing the range of motion or too narrow and having the grip get in the way of the knees. However, If they set their shins forward first, this eliminates the possibility of setting their grip too narrow since they can now set their grip around their knees which stops them from being able to box them in and limit external rotation. This also means the grip width now always accommodates the stance width and degree of toe out the lifter has chosen, and the grip width will always self adjust if they accidentally take a stance that is wider or narrower than usual.