In no particular order.
I believe the sequestrant is for plaster dust, but it may be for metal, not sure.
I like your plan for the water, but you are risking your warranty if you do virtually anything to it. I would want to do what you're suggesting (I did, in fact), but I can't actually advise that (my pebble was from a local source, so PebbleTec was not involved). Unless you can get something in writing from the PB that he is OK with your plan. I think that's important. It's an unfortunate situation, especially for someone as pool-savvy as you, but that's the industry. See if the startup guy will work with you. Get the PB behind that, in writing if possible.
Don't be shy with the pump speed. The faster you suck any particulate (plaster dust) into your filter, the less of it will stick to your brand new finish. That's what the 24/7 pumping and multiple-times-a-day brushing is all about. Maybe not top speed, but near the upper end. Especially the first week. I let mine run for a month!
Personally, I wouldn't use tabs at all. Save them for when you need to add a little CYA next year. Especially with that warning about their use from PebbleTec. This is the only time you're going to
know that your CYA is 0 (fill water has no CYA), and so be able to accurately dose with granules. That's assuming you verify your water volume with the meter trick. You can't really trust the PBs number, it's common for PB numbers to be even wildly off. Even with a good number, I would suggest you put in, say 75% of your CYA. Give that several days, and then test. It's not hard to overshoot CYA (the test itself is the biggest factor in deviation). If it tests at 75%, then your volume and testing procedure is likely good, so then go to 90%, wait a few days, test again, then top it off. Sneak up on the number to avoid overshooting, while gaining confidence with the test (it's a bear).
Your pH will not be too low. Even if it somehow is from the fill, don't push it up. The pool will do that in short order, like almost immediately. Stock up on acid, don't run out. pH is critical at this point. Any surplus will last (it doesn't go bad, really), and you'll be using that up anyway in the first year. And then some. (Keep those lemonade-looking jugs away from your kids!!)
I'd wait a week to put anybody in, at least. That's more of a rule for plain plaster, but I think there's something to it even for pebble. And even then I'd want an email from the PB saying it's OK to go in (warranty, warranty, warranty, warranty, warranty... getting the theme here?

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Check on the first allowable use for a vac, too. Different schools of thought on that. And again, more for plaster. Ask your PB to add that to the email! But I'd wait a while anyway, even if he says it's OK.
You already know this: now's the time to spend a little more: money
and effort. A little more electricity for the pump. Brush more often than they say. Wait a little longer for "firsts," etc. You won't get a second shot to do this as best as you can...
Did I cover everything? We most differ about the pucks. Do think that through...