I'd save the substrate you have as well....keep some of it in there if you can, even if its only in a mesh bag temporarily.
I did this last year for my 75, drained half the water, took all the fish out, all the hardscape........it took me all day I can tell you that much for certain.
Didn't help either that I started with very few plants. Do yourself a favor and have a ton of plants on the first day.
I'm assuming when you say you have 30 fish that they are smaller fish right?