Your looking at a few factors
1). Your letting your new rock cure allowing the die off to already happen. Good thing
2) you already have water and live rock that has the good bacteria already in it another good thing
3) you have live sand that has more good bacteria
Given those three things working in your favor I would aqua scape with the new rock first to get your base....then put the sand in. Then I would move the live rock from the old tank. I would remove the corals from the lr
and just put them in the bottom of the old tank...that wa you can move all the lr
over...then transfer a good portion of the old tank water to the new tank...obviously leaving enough for the fish and corals to stay In for a little bit..
Then add your new water...test your parameters....I would be surprised if you even saw a mini cycle and if you do it should be mini.