It can happen a looooot of things, better you start and tell us if you find a problem, if will be just first orchestral work don't try to go too far.
In my case, I never write reductions, I write directly for all, very often my imagination goes too fast and I write the ending just after starting, so I write a work for my ending, in the middle part usually I write something, one page, next day I write another page, next day I listen and I don't like it and delete the whole thing and rewrite, that's why I'm so slow, I write like 1 + 1 + 1 + 1 + 1 - 4 + 1 + 1 - 3 + 1 + 1 + 1 + 1 + 1 + 1 - 7 etc I reject so many ideas