My method is to put all of the houses in a corner of your island you know for a fact won't be worked on right away (not on the beach as you can't fit all 10 plots plus your house and everything else there). From there, do your terraforming in a smaller area first, like around Resident Services. From past experience flattening an entire second island myself (twice), I find it hard to come up with anything creative if I clear an island completely compared to working on a small section and moving on to the next. Working in sections can maintain some form of creative spark, so that you're not bored to tears trying to do it all at once in one day and bam, you're burned out. Time travelling might help speed up the process, but I understand that not everyone's a fan of it despite not having any game-breaking consequences.
It's best to move the houses in the proper spots after you get a visual idea of what a section will look like, so that you're not wasting bells and time. As villager houses are 4 wide and 3 depth across (door on the right side), I would make a custom ground design that is a bright color, so you can temporarily place a 4x3 template on where a house might go, and then ultimately place the plot there once you design the space around it to your liking.
tl;dr - Don't flatten all at once. Move everything to one corner of the island, start around Resident Services, and work your way through.